Shock Therapy - An Athlon64 / FX Power Supply Guide

Question

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

Answer 1

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.