ATX Power Supply +28V Step-Up Voltage Regulator How to

I'm going to try this with an atx supply for a spare MDD I have.
Here is the schematic:
http://homepage.mac.com/baakre/public/files/28v_vreg.pdf
Here is a thread on a diy job (have not finished reading it so I don't know the results yet)
http://episteme.arstechnica.com/eve/forums/a/tpc/f/8300945231/m/4820959925/p/2

Look in the example finder for DAQmx functions for analog input and analog output.

Similar Messages

ATX vz µATX Power supply form factor.

There are two types of power supply (socket??) available in the market nowadays. They are ATX and µATX.
- How are they differing from each other?
- Are they interchangeable each other?
Say I have MSI785GM-E51 mother board which has ATX form factor while the power supply is µATX, can I use them both/powered the M3A785GM-LE/128M with those ATX power supply?
Or can I convert the µATX to be ATX form factor?

The motherboard mentioned is mATX not ATX 785GM E51. M=mATX (µATX). It's made to fit the smaller cases but can also be used in the larger mid-tower & full tower cases if that's what you have.
µATX PSU has a different size case and mounting dimensions to fit the small mini tower PC cases and also the smaller HTPC cases. Power connections are pretty much the same between the 2 but mATX generally don't have as many power plugs for HDD & ODD.
Due to physical dimensions and different mounting they are not interchangeable.
There are many variables involved in selecting a PSU beginning with what type the PC case itself requires. If you need suggestions on what to get we need to know what CPU, on-board or dedicated graphics you will use, how many HDD's.

Want references for using ATX power supply with MDD.

There are references all over the place to adapting an ATX power supply for a MDD/FW800. But it would be nice to have links to as many useful ones as possible in one thread -- this one -- without too much superfluous verbiage.
Please post links with brief descriptive comments or, if you have some hard information that's not easily linked to, please post it as concisely as possible. Hopefully, the resulting thread will be useful to many people, and not just to me.

Watch these great YouTube videos
http://www.youtube.com/watch?v=xICg592xJTg
http://www.youtube.com/watch?v=j7RDGy34tjU&feature=fvw
Look at these links.
http://efeion.blogspot.com/2007/12/power-supply-fun-part-2.html
http://www.applefritter.com/node/23857
 Cheers, Tom

Why does my FP-1600 take a 24V .5 Amp Power Supply and drop the Voltage to 11V at .5 Amps?

I have a FP-1600 connected to 4 FP-TB-1 bases. 2 FP-AI-100, 1 FP-TC-120, and 1 FP-AO-210 modules. I am powering the FP-1600 with a 24 V .5 A power supply. There are no devices currently connected to any of the modules. The power supply should be supplying 12 W, which should be enough to power the FP-1600 and the 4 modules according to the power requirement calculation in the manual P = 7 W + 1.15*#modules. When I install the third module, the FP-1600 stops communicating. Checking the power supply I see that the voltage drop across the power terminals on the FP-1600 is only 11V and then measuring the current being drawn it is .5 Amps, which is only 5.5 W, not enough to power the devices. When I unhook the power supply and measure the Voltage it is 24 V.
Why is the FP-1600 dropping the Voltage to 11V? Should I just purchase a 12V 2 Amp power supply?
Thanks for any help
Jeremy

Hello jqk,
You got it figured out. The maximum current that can be drawn is .5 which is too small. As the current being drawn approaches the maximum allowable current, the voltage will begin to drop. Eventhough the current you measure is .5A, the fact that the voltage is 11V means that the circuit requires more current to function properly.
As a rule of thumb, you want the maximum current your power supply can deliver to be at least the double of the system's maximum current consumption.

How to control HV power supply (0-5V control voltage)?

Hey there,
I (LV newbie) wonder how to control my DELTA ELEKTRONIKA Powersupply with Labview. The control interface is a 0-5V analog input to set the power supply's output current.
Also I want to get some feedback of the set power supply current from an second (GPIB-controlled) instrument.
So how do I have to program a closed loop contol (application is not time critical), cause it would be mixed up of controlling by analog out (0-5V) and feedback loop driven on the GPIB-Card?
For a first step a simple control loop to set the current and monitor it on an analog input would also be an assistance .
THX for anyone helping

Look in the example finder for DAQmx functions for analog input and analog output.

Suspect dead power supply -- next steps, recommendations?

Hi all!
Our 17" iMac won't power on and I suspect it's the power supply (I tried different outlets and power cords). What should my next steps be? For example, while browsing I saw mention of LED indicators inside the unit. Is that the next logical step?
I don't necessarily want to continue using the iMac since I have a much newer MacBook Pro that I can use instead. However, I would like to get all my iTunes files off the iMac (I have a backup that's two months old, but I've purchased a lot of music/apps/videos since then). So if it's easier/cheaper, I'd be open to suggestions other than fixing the iMac. For example, can I pull the hard drive from the iMac and get some sort of external enclosure so that I can plug it into my MacBook Pro to copy the files off? If so, what sort of enclosure would I need for the iMac's hard drive (links?)
Thanks so much in advance!

Good old Apple forums. My iMac wouldn't start up and the first post on the list this past Thursday was this thread!
The machine had powered itself down twice and the last time I couldn't start it up. I did do a backup the night before.
I did the LED test all the way thru. Nice to learn that one. After #12 indicated my logic board needed to be replaced, I made a Genius appointment for two days later. There, Andrew at the Walnut Creek, CA store opened up the machine, saw that the condensers were fine and sent the machine upstairs for a new power supply. He said that sometimes the LED test will indicate the logic board, but most of the time it's the power supply. $85 each for the part and labor = $170. Much cheaper than the alternative.
Now that was one of my better Apple Store experiences.

Corsair - Professional Series Gold 650W ATX Power Supply

Hello Best Buy community,
I recently placed an order on 01/02 for a power supply. As my computer is down without the part and school is fast approaching (obvisouly I need the PC), I went with Best Buy for express shipping and the estimated delivery date of 01/04-01/05. It's now 01/04 and my order is still processing. I waited for 25 minutes to speak to "customer service" only to be told that the product is a "special order item" but the estimated time of delivery is still 01/04. I'm bright enough to know that an order that hasn't been processed yet today holds no chance of arriving tomorrow. The customer support rep didn't share that same idea, read the info I could check via email myself, and got quiet until I said "thanks for the help".
Upon browsing Best Buy online again, I have noticed that the product is now "sold out online". What is going on? I need this part. Why was I not informed out right my product ordered wasn't even in the Best Buy warehouse, is considered "speicial order", and my wait could be longer because of that?
Solved!
Go to Solution.

Well, your first mistake was buying something from Best Buy in the first place. Unless it was an emergency, their PC components are way overpriced.
You should have either gone through "Newegg" or "Tiger Direct", better service and way better prices all the way around.
Apparently, there's more than enough sheep that enjoy bad customer service, unknowledgable service, and overpriced merchandise to keep Best Buy in business.

Power supply and system operating voltage question

This is my system
MSI Neo2 Plat 939 Soc
AMD 64 3500
OCZ 1 Gig
40 G Western Digital (OS)
160 Seagate (everthing else)
PSU 550W Aspire Chameleon
+3.3 = 32 A
5+ = 34 A
12+ = 36 A
-5 = 0.3 A
-12 = 0.8 A
+5 VSB = 2.0 A
NO overclocking
The voltages my system is running are
CPU Core = 1.09 V
+3.3 = 3.31
+5 = 5.01
+12 = 12.65
Do these look OK?

Is your cpu core only 1.09 due to cool and quiet because that is what mine is now running at when i enabled c 'n quiet. Also i have a 520 watt aspire psu, but my voltages are very close to the mark 12= 11.96-12.01, 5=4.98-5.01, and the 3.3 = 3.3 but my cpu core is around 1.41 with no cool and quiet and around 1.09 with it on. I am also using the neo4 plat/sli, maybe better voltage regulators, im not to sure but i would think if you arent having any reboots that your board should be fine just dont know in the long run. If you could maybe try a friends PSU and see what you get and if it is around the same your PSU should be fine.
Andrew

How do I use LabVIEW to control and vary the voltage on my Agilent Power Supply and simultaneously record temp from 1 DMM and voltage from another DMM?

I am using an Agilent Power Supply to apply a voltage to a
thermistor to heat an Al chassis. I want to use LabVIEW to tell
the power supply to apply 5V for 10 minutes, then step to 7V for 10
minutes, etc. I am completely new to LabVIEW, so any help would be greatly appreciated!
In addition to that, I want to place a type J thermocouple onto the Al
surface and use a Keithley 2000 DMM to monitor the temperature (it has
a built in conversion from V to Temp for type J). I will also be
using another Kelthley 2000 DMM to record the output voltage of a new
uncalibrated thermocouple. I would like to collect the output
voltage for this uncalibrated thermocouple and the temperature reading
from the type J simultaneously. How should I go about doing this
in LabVIEW? I will be using version 6.1. The power supply
and DMMs will be connected to a PC using GPIB.
Again any suggestions would be greatly appreciated- I have no idea
where to begin on such a project. I have taught myself how to
make a basic VI- converting temp in oC to oF, but that is as far
as my knowledge goes.

What you want to do should be fairly straightward and a good way to learn labview.
First off, if you haven't already, I would download the drivers for the Keithley and Agilent instruments. I found the keithley drivers at the link below. You will need to find the labview drivers for the Agilent PS at their website. Drivers are the VI's you will use in your program to control the insturments.
http://sine.ni.com/apps/we/niid_web_display.download_page?p_id_guid=E3B19B3E90B0659CE034080020E74861
If you open Labview and go to the help menu and click on Labview bookshelf there is alot of information on getting you started coding labview. This should get you started, if you have anymore questions just ask in this same thread and I am sure you will get all the help you need.
Brian
Message Edited by BrianPack on 09-14-2005 05:21 PM
Message Edited by BrianPack on 09-14-2005 05:21 PM

Shock Therapy - An Athlon64 / FX Power Supply Guide

I used to make a hardware list of all the components I would like to incorporate in my next
computer build. Normally...at the bottom of that list would be the power supply, not that I
didn't think it was important, it's just that my other hardware was so interesting! Today, power supplys
seem to take a back seat to blazing-speed CPU's, Dual-Cored processors, glitz and glamour
video cards...not to mention supersonic, heat-sinked RAM and modular, gizmoe'd PSU's promising not
only over-achiever specifications, but eye-candy as well. The lowly PSU....tucked up somewhere inside
it's dark and lonely loft....effortlessly supplying us with the energy required for important 3D imaging
or just funning with the latest games.
What a power supply does is rather simple. It converts your office or home's socketed electricity to
usable 3.3v, 5.0v and 12.0v energy...that's all. A power supply that cannot efficiently do this will-
over time-cause computer crashes, continuous reboots and shutdowns, and worse...expensive component damage.
And now, with faster processors such as AMD's Athlon64 and FX line of CPU's, never has there been a time, when
choosing the right power supply is so important! This article is written for those using these high-powered CPU's!
Well...Do we have your attention!?
If you are experiencing these problems, or still scratching your head over that last RMA....could be
your PSU is trying to tell you something.
To begin with, a power supply's ratings refer to its maximum output under ideal conditions. No power
supply is 100% efficient. In high-quantity manufacturing, power supplys may not put out any more than 60% of
their advertised specifications. In any PSU, that rating can be further reduced by the effects of heat
and electro-magnetic radiation. That's where "switching" power supplys come in. A switching power supply draws
only as much current that is needed from the AC input. Buying a hefty PSU with this feature will guarantee
that you will be paying no more for electric service, than you would with a cheaper, less powerful unit.
One of the most common causes of power supply inefficiency, and ultimately failure is dirt. Dust and
foreign materials can cause the beginning of the end for a power supply, by attacking the fan first.
It begins by slowing the fan down...thus creating heat through friction, then ultimately burning it out.
PSU's with high-quality ball bearing fans are a must. They are far more durable, and not as likely to
become noisier as time goes by.
As a general rule...a failing PSU will usually emit abnormal sounds, followed by unstable voltage readings....
then the computer crashes or lock-ups, with random shutdowns, and sometimes...refusal to even power-up.
If you think your power supply is on its last leg...better to deal with it now, or face the more serious dilemmas later on.
APM (Advanced Power Management)
APM is a feature originally developed by partners, Microsoft and Intel. It relates to a systems ability
to utilize different states in regards to a systems utilization of power. On, Off, Standby and Suspend
are examples...these are BIOS features, not PSU functions. APM only requires of the power supply, the
function to turn power on or off through an electrical signal, and the presence of stand-by voltage.
All ATX power supplys are required to incorporate this feature. However, if some components in a computer
are not APM-compliant, your system may encounter errors or freezes when going into hibernate or stand-by
modes.
ACPI (Advanced Control Power Interface)
It's the latest power management control that was developed by a conglomeration of IT corporations. This interface
is O.S. derived, rather than BIOS, and all ATX power supplys should be ACPI-compliant. You should not have to be
concerned about this feature.
Line-Conditioning Circuitry
A power supply component that helps control power levels, spikes and surges in
the most unreliable of home sockets.
EMI Filter
This circuitry smooths the fluctuations of incoming AC currents, also known
as Electro-Magnetic Interference - EMI filters are usually found in higher-end power supplys.
PFCC
Power Factor Correction Circuitry...smooths out sudden, initial spikes in power
delivery - reducing amplitude and preventing circuit overloads.
Connectors
There are five main connectors found on the latest version ATX power supply.
1) ATX main power connector - 20-pin, 24-pin, and 20 to 24-pin adapter.
2) ATX 12v power connector (4-pin to CPU)
3) Molex peripheral power connector
4) Floppy power connector
5) Serial ATA power connector
On newer SLI-certified power supplys, you'll find two 6-pin video card connectors.
Know What You Need
When purchasing a power supply, make sure your parts list is all-inclusive...know ahead of time, what you expect to
install in your system. You should also visit the motherboard manufacturer's site, as well as the CPU's. Most of the
products will have specifics regarding power supply requirements needed for that specific component. Unfortunately, you
really won't know how well the PSU performs until it is installed and running your system (hopefully!) This is the main reason we
recommend the most popular brands - power supplys that have shown a duration of manufacturing quality over the years. Those are
as follows: Antec, Enermax, OCZ, PC Power and Cooling, Tagan, and a few newcomers such as SeaSonic and Silverstone are
worth looking into.
If you believe you have found the PSU of choice, remember this: AMD recommends a minimum 350 watt power supply to run
Athlon64 and FX CPU's. To that, add the 30% for power lost to heat, and the subsequent electro-magnetic radiation. Hold on with that
calculator...throw in an additional 40% to 60% for the "potential" inaccuracies of specifications inherent in mass-produced electronics.
Pay special attention to outputs on either single, or dual rail +12v lines. A motherboard, CPU, and graphics card can consume up to
150 watts alone - before hooking up your remaining components. If running an SLI configured board, look for a PSU that is certified
to run that configuration...there's only a few PSU's that lay claim to that!
Broken down, you can look at it this way: An Athlon64/FX processor can use up to 90 watts off the +12v rail. High performance RAM
can take in about 25 watts for each stick of 256MB system memory from the +3.3v line. PCI cards will use about 10 watts each, while
an AGP video card can consume about 50 precious watts alone from the +5v or +12v. Hard drives? A 7,200 RPM drive...about 15 watts
each, taken from the +5v and +12v rail. Finally, but not absolutely is the optical drives...robbing about 20 watts each, also from
the +5v and +12v lines. So you see....not only is the +12v amp ratings of concern, but also the +5v line!
In doing the math...on a system incorporating an Athlon64 (say a 4000+), 2 sticks of high-end RAM, 2 or 3 PCI cards, 1 mid-to-high
end AGP video card, 2 ~ 7,200 RPM hard drives, and a couple of CD/RW or DVD/RW opticals...you're looking at a "base" requirement of 270 to 325 watts. That's for a running system...now figure boot-up loads, 30% for heat and radiation bleed-off, then a 40% safety factor for manufacturing inconsistencies...you've got a power supply in the 450 to 520 watt range!
Modular Power Supplys:
The pins that are used for the modular plugs are not very good at passing current. It's basically electrical resistance between the male and female components, and voltage "drops" are likely. In real world events, they will become loose, dirty, corrosive, and eventually burn. You can figure about 10% less efficiency with a modular power supply.
Now you can understand how manufacturing "tolerances" that are inaccurate by 40% to 60%, can have such a devastating effect on
the performance of your new system. If you follow these simple guidelines, bearing in mind the hardware you will be using, and what
your intended use of the computer is for...then it will be one less dramatic incident when pushing the power button for the first time!
Here's a neat little tool....a bit out of date - that can give you a basic idea of what you'll need in a PSU.
You can apply the percentages above, for an even more accurate assesment of your PSU requirements!
http://www.jscustompcs.com/power_supply/Power_Supply_Calculator.php?cmd=AMD

Quote
In doing the math...on a system incorporating an Athlon64 (say a 4000+), 2 sticks of high-end RAM, 2 or 3 PCI cards, 1 mid-to-high
end AGP video card, 2 ~ 7,200 RPM hard drives, and a couple of CD/RW or DVD/RW opticals...you're looking at a "base" requirement of 270 to 325 watts. That's for a running system...now figure boot-up loads, 30% for heat and radiation bleed-off, then a 40% safety factor for manufacturing inconsistencies...you've got a power supply in the 450 to 520 watt range!
Well, except the CPU, my system has all that you mentioned there (I even have 3 optical drives). And my 350W PSU has been rock solid for more than a year (BeQuiet, = Tagan, IIRC). I don't think a 4000+ needs 100W more than my 3200+ . And that link you posted says that the minimum recommended PSU for my system is 506W xD. Come on.
Oh, and in the place I work there are 6 amd64 with GeForce 6800 GT and 2GB RAM with 380W Antec PSUs. All 100% stable, of course.
I would only go for >400W if I wanted to do extreme OC (with overvolting), or SLI. Otherwise, a good brand 350W PSU is more than enough.

Cisco Power Supply error

What does out of regulation limits means ?
1 red "OUTPUT FAIL," normally is off but illuminates when power supply outputs are out of regulation limits
Thanks
Rosa

Hi,
Seet this:
LED
Meaning
INPUT OK
AC-input power supplies:
•Green—Source AC voltage is OK. (Input voltage is 85 VAC or greater.)
•Off—Source AC voltage falls below 70 VAC, is not present, or the PEM is turned off.
DC-input power supplies:
•Green—Source DC voltage is OK. (-40.5 VDC or greater.)
•Off—Source DC voltage falls below -33 VDC or is not present at the PEM.
FAN OK
Green—Power supply fan is operating properly.
Off—Power supply fan failure is detected.
OUTPUT FAIL
Red—Problem with one or more of the DC-output voltages of the power supply is detected.
Off—DC-output voltages within acceptable margins.
Note For proper operation of the OUTPUT FAIL LED, systems with single power supplies must be configured with a minimum of one fan tray and one supervisor engine. Systems with dual power supplies must have a minimum configuration of one fan tray, one supervisor engine, and one additional module. Failure to meet these minimum configuration requirements can cause a false power supply output fail signal.
This is for 6500 switches but apply to almost all models.
http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/hardware/Chassis_Installation/Cat6500/0apwsply.html#wp1025570
Hope this helps.

How to check the power supply? iMac G3 233

How to do it?
Can i just take the case with the mainboard out and "short" the pins Power on (pin 8) with GND and check the voltages on the connector that comes out of the monitor case?
I know that the pin 8 is the power from articles about imac>atx case conversion.And i know that you can power up a normal ATX power supply by shortening two pins, and want to know if i can do the same with iMAc power supply. I don't want to fry anything.

Sounds like you have eliminated most of the possibilities, other than power supply board or motherboard. But it may also be the CPU daughter card that is faulty. I had one (233 MHz) that would run Mac OS 9 just fine, but it was unable to run Mac OS X reliably (crashes and freezes after a few minutes). I replaced it first with a 333 MHz G3 card off of eBay and later with a 467 MHz G4 card from the Fastmac booth at MacWorld San Francisco two years ago.
If you are comfortable disassembling the iMac to the point of removing the power supply board, you can layout the PS board and the carrier assembly (the thing you pull out with the motherboard, CPU card, and drives) on a table top. Then connect the power supply board to the carrier assembly, and connect the external power cord plug to the power supply board, and connect a keyboard with a power button to the carrier.
To measure the voltages, you can disconnect the 4-pin connector to the hard drive. If you turn it on using the power button on the keyboard, it will not start up with the hard drive not powered up (unless you use a bootable CD), but the system should be powered so that you can take your measurements.
Hope that works. Be careful with the exposed back end of the CRT. Keep any curious cats out of the room while you do this...
In case you don't have the PDF of the tray-loader iMac tech manual, it is downloadable here.
http://www.baconeggs.co.uk/manuals/index.htm

Quicksilver G4 Dual 1ghz power supply...

I'm pretty sure that the power supply in my Quicksilver G4 Dual 1ghz is going. Initially, I was only getting the familiar bong for startup, but nothing else. I then noted that the fan on the GForce Ti card wasn't spinning, nor the fan on the optical drive. I removed the Ti card, my second hard drive, and two RAM chips; the computer started, then shut down. I pushed the power button, it finally started. The fan on the optical drive is still not spinning (still plugged in though.)
I did buy a new motherboard battery, put it in, and followed the process of resetting the CUDA/PMU. I did that before doing the above so I know the battery is fine.
That's why I'm almost sure it's the power supply.
So, my question is, where and how do I go about purchasing a new power supply for this computer? Any help and/or suggestions would be most appreciated.

Some of the symptoms might desribe a logic boarrd, cpu or Power Supply issue. This article might assist:
http://www.peachpit.com/articles/article.asp?p=420908&seqNum=4&rl=1
If you are extermly confident with a multi meter you might try the following procedure. However, be sure to use appropriate ESD procedures as "static" can kill your machine and be sure to take care as electircal power can kill you.
PS verfication:
1. Power Mac G4 (QuickSilver/QuickSilver 2002) (see Figure 3): Connect the black lead of the volt meter to pin 11 of the 22pin power supply connector. Connect the red lead of the volt meter to pin 22 of the power supply connector. The volt meter should measure approximately +25V. If you do not get a reading of +25V, re-check the volt meter connections and measure the voltage again. If voltage is still not present, replace the power supply; otherwise, go to the next step. If you do measure +25V on pin 22, the power supply is likely OK. Go to the next step for further verification.
Start up the computer by pressing the power button on the front of the computer. Note: Verify that the power cable is plugged into connector J30. If the computer starts up normally, the power supply is OK. If the computer does not start up, go to the next step.
2. Check to see if the power supply fan is spinning. If it is not, go to the next step.
3. Connect the black lead of the volt meter to pin 16 of the power supply connector for AGP and PCI models or pin 11 for Gigabit Ethernet/Digital Audio/QuickSilver/QuickSilver 2002 models. Connect the red lead of the volt meter to pin 1 of the power supply connector. The volt meter should measure approximately +3.3V.
If you do not get a reading of +3.3V, re-check the volt meter connections and measure the voltage again. If voltage is still not present, replace the power supply; otherwise, go to the next step.
4. Connect the black lead of the volt meter to pin 16 of the power supply connector for AGP and PCI models or pin 11 for Gigabit Ethernet/DIgital Audio/QuickSilver/QuickSilver 2002 models. Connect the red lead of the volt meter to pin 4 of the power supply connector. The volt meter should measure approximately +5V. If you do not get a reading of +5V, re-check the volt meter connections and measure the voltage again. If voltage is still not present, replace the power supply; otherwise, go to the next step.
5. Measure the voltage of pin 10 on the power supply connector. The voltage should measure approximately +12V. If you do not get a reading of +12V, re-check the volt meter connections and measure the voltage again. If voltage is still not present, replace the power supply; otherwise, go to the next step.
6.The testing is complete. You have just verified that the power supply is not the cause of the “No apparent power” symptom.

Guide for Selecting a Power Supply

Mod may want to make this a STICKY.
Here's a general guide on how to select a PSU for your HP desktop. The majority of standard ATX powersupply (PSU) should fit inside an HP case. The exception would be a slim line case or the esoteric Blackbird.
Look for an 80+ certification on the PSU to save electricity. A PC will normally idle or run at low load 75% of the time. Therefore, look for a PSU that's more efficient in the 50-90W range. An 80+ 350W PSU reaches the 80% efficiency level at 70W output (20% of rated output). The output must be greater than 140W to achieve the same level of efficiency from an equivalent 80+ 700W PSU. So picking a PSU that is rated 25% higher than the maximum ACTUAL load of the rig will save you more $ on electricity.
A modern PSU is designed to achieve peak efficiency between 20 and 80% of the rated output. Running a PSU above the 80% load level will result in excessive heat, noise, and premature failure.
An Nvidia rig with GeForce GTX 280 (1024MB on board RAM) will draw about 350W max from the wall. If we factor in the efficiency of a 80+ PSU, then the actual load on the PSU is only 280W (350 x 0.80). To calculate the required PSU, multiply the actual load by 1.25 (25% margin). In this case we only need a 350W PSU (280 x 1.25) to run this GPU.
Let's apply what we know to a Radeon HD 4870 (512MB on board RAM) rig. 290W max from the wall. Actual load is 290W x 0.80 or 230W. Now apply the 25% margin rule and we arrive at a PSU requirement of 290W (230W x 1.25). Even if we apply a 50% safety margin, the power requirement is still under 350W (230W x 1.50).
There is no need to overspec the PSU by 50% unless you run your PC at full load 24/7. Keep in mind that there is a huge variation in PSU quality and rating. A cheap 500W PSU may not be able to deliver as much power as a quality 350W. Antec Earthwatts/NeoPower/TruePower, Corsair, and Seasonic are quality units widely available at many US retailers.
Many high-end PSUs will need additional power from the PSU in the form of one or two 6/8 pin GPU power plug. You can purchase an adaptor to convert a 4-pin molex to 6-pin GPU power plug.
http://www.tomshardware.com/reviews/geforce-radeon-power,2122-3.html
This question was solved.
View Solution.

Found a review of the Corsair 400W (Seasonic-built power supply) that I've been recommending on this forum. This ATX power supply should fit inside most HP case (minus Slimline). It has ample power to drive a modern quad core plus Radeon 4870 or GTX280 video card.
At 100% load, we see a 2.5% drop in the +12VDC rail, which is still within spec and does not affect the performance of any component inside the PC. +12VDC regulation at 82% load is a superb 0.5% with 45C case temperature. Note that the power output and efficiency decrease with higher temperature.
Cheap power supplies are rated at 25C. When these units are subjected to higher case temperature, the output can drop 10-20%.
Again, we discover the sweet spot of a good PSU is 20-80%. A good 400W PSU is more than adequate for many PC users. This Corsair is only $30 after a $10 rebate. That's a great price for a quality/quiet PSU that won't put a huge dent in your wallet.
http://enthusiast.hardocp.com/article.html?art=MTYwOSw1LCxoZW50aHVzaWFzdA==
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Additional 20% off w/ promo code "Mar20", ends 3/31
Message Edited by RoyalSerpent on 03-08-2009 11:40 AM
Message Edited by RoyalSerpent on 03-08-2009 11:42 AM
Message Edited by RoyalSerpent on 03-08-2009 11:45 AM

Power supply in MDD dual 867 shot?

I arrived home today to find that my Dual 867 G4 was powered down, though I had left it on when I left this afternoon. Not only that, but it won't turn on at all - the power button doesn't light up, there's no spinning of the disks, no chime, nothing. I've unplugged and re-plugged the power cord, switched out surge protectors, plugged it directly into the wall socket - no dice. One thing I did notice, though, is that when I plugged the power cord into the back of the G4 after I had disconnected it, I hear a very faint and periodic short noise, maybe every one second, from the back of the G4. Almost like a short buzzing noise, but too quiet and brief to really be called that.
Does this sound like the power supply is shot? Like it's shorted or burnt out in some way? Thankfully I have two iBooks to use in the meantime, but most of my daily used files and such are on the 4 hard drives in the G4, and there's no space for them (particularly my music) on either of these laptops.
If I do need a new powersupply, does anyone have recommendations for sources? It seems sellers on ebay want the sell them for over $100.
Thanks,
Anthony

Hi,
Yes, that does sound like a power supply issue. It could also be a bad CPU card, or even the motherboard. To isolate the problem, I'd take out the power supply and measure the voltages across the different pairs of wires in the plug that feeds the motherboard. If the voltages don't equal what they should, as per the G4 MDD service manual, then you're in the market for a new power supply. And yes, the ones on eBay will go for 100-150 or so. Make sure it's stated to come from a working system. Untested power supplies could be dead ones from a similar dead machines.
If the power supply voltages are OK, then to isolate whether or not the motherboard, or CPU card is bad will require a spare motherboard, or CPU card, to swap with yours.
Sources for new, or rebuilt, power supplies include WeLoveMacs , DVwarehouse, HarCoreMacs , among many others.
Here is a good set of pictures and step-by-step instructions on taking the MDD power supply apart.
In my case, I had a spare motherboard and power supply to test with. The machine, which I got cheap off of eBay because it didn't work, did not turn on at all. Swapping first the Power supply with a good one didn't bring it back to life. Turns out the CPU card and the power supply were both bad. Once both were replaced, the MDD machine has worked fine.
Good luck!
Ed

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