K9N SLI suddenly shuts down!

Question

K9N SLI (not platinum) bios 3.1
AM2 X2 3800+
Zalman CNPS 9500
2x1GB DDR667 Team Value (5-5-5)
Sapphire X1800GTO2 512MB
Hitachi SATA1 160GB
Pioneer DVR-108
LC Power 560W Titan:
3,3V: 35A
5V: 40A
12V1: 18A
12V2: 18A
two 80mm fans taken from a PSU
Zyxel external ADSL Modem
Operating System: Windows XP SP2
The Problem
The PC suddenly shuts down as if the power cord is pulled from PSU.
Detailed Description and what I've tried
The first days after I've build the system everything looked to work properly. I tried to run 3d mark 2005 and it ran without problem. Then the fourth day when I was surfing on internet and listening music with winamp, suddenly the pc shut down. This happens three times and I noticed that it depended from the audio device of the MB, in fact if I didn't play music the pc didn't switch down, otherwise after about 20minutes I played music, the problem occured.
So I thought the problem was the PSU, so I ran 3d mark 2005 for more than an hour and it ran without any problem! I was very surprised. I tried also to run Prime95, one for each CPU core, and also Prime ran without problem.
Another problem was that after about 1-2hours that I was connected to internet, the connection suddenly freezed and the OS couldn't shut down the pc, so I had to use Reset button.
After someday I noticed that the motherboard has 3 power connectors!!! I've connected to the PSU only the 4pin and the 24pin!! So I connected also the molex to the PSU. So I thought to have found and solved the problem, and for about 48 hours the PC worked properly, also for 6 continous hours, I can play music using the Realtek audio device and no more problem with connection.
But then again after about 48hours the same problems!!
So I've tried to disable the realtek device and to use a sound blaster 1024 Live! And it seems to work, I can play music and the system doesn't shut down. I've also disconnected the two 80mm fans, it seems to help.
Another strange thing is that now when I switch on the system the MB emits two short beeps. Before it emited one long beep. What does it mean? I don't understand the cause of this change.

Answer 1

True, the computer doesn't need that amount of power.....but....
You are miscalculating the powersupply.
Just because it states it can do 17A (or what ever figure) it doesn't do that all the time.
Here you have the details of how a PSU handles output, then you might have a clue what we are talking about:
Quote
3) Specify a low operating temperature for rated output. This is quite common, but again not often seen in consumer brochures, but rather tech spec sheets provided usually only on demand by engineers or corp buyers. A typical PSU operating temp statement is somthing like this:
0?C ~25?C for full rating of load, decrease to zero Watts O/P at 70?C
Examine what that says. Full power (let's say 400W) is available when the unit is at 0?C ~25?C. Hmmm. Think about this.
Have you ever felt air blown out of a PSU in a PC running absolutely full tilt (which it would have to do to get anywhere near 400W output) that felt cool to the fingers? 25?C airflow would feel exactly that: Cool, given that normal body temperature is 37 ?C.
So this PSU cannot deliver full rated power when its temperature goes over 25?C. OK, what happens to the max power output capacity above that temp? It decreases gradually so that by the time the PSU temp reaches 70?C, the PSU cannot deliver any power at all. So if you assume that this power drop as temp rises is linear, then max power capacity will drop by ~9W for every degree over 25?C.
Now having examined as many PSUs as I have over the last 2~3 years, I have to say there's not a single PSU in ANY PC I have ever used or examined that would not measure at least 30~35?C almost anywhere inside the PSU under almost any kind of load. And if/when it is pushed, 45?C is nothing at all, especially for or near hot running components like voltage regulators.
So let's say 40?C is a fairly typical temp inside a PSU. This 400W rated unit would actually be able to deliver a max of just 220W at that temp. Hmmm. Interesting, isn't it? At 50?C, the available power would drop to just 130W. No wonder some PSUs have 3 fans each capable of 50 cfm!!
Here's a simple fact: Really high quality PSUs are actually rated for full power output at as high as 50?C. The trick is get a hold of the spec sheets that tell such information so you can compare apples to apples. Or ask.
Source: >>SilentPCreview<<
I suggest you start reading on their site as to what they have to say about powersupplies.
As those PSU's DO NOT DELIVER the amount of power under all conditions....many people have blown their system to pieces already by ignoring the heat-factor.
That is we are telling all along, you don't need 33Amps....but you need loads of headroom when summertime temps are there.
Because then your PSU doesn't deliver near the ammount of power you think it does.
Also, split rails are far worse then single rails when it comes to that...heck a lot of so called splitrails are not splitted at all, like the some of the Coolermasters....
Do yourself a favor and get to know how PSU's work, as they are NOT what you think they are.
And to quote a bit more from the same source:
Quote
What's really interesting is that Intel has tacitly waived the 240VA limit requirement in its PSU validation program for the better part of a year. Intel maintains a web page listing all the ATX12V they have tested that "meet MINIMUM electrical, mechanical fit and functional compatibility" with Intel desktop boards and processors. For the 32 ATX12V v2.2 PSUs tested in 2005 that are on this list, 17 models are identified as having at least one output line that exceeds 240VA. And yet, these 17 models are on Intel's approved list.
According to the engineers I spoke with, the majority of these 17 models have just one 12V line. They also point out that there are another 20 or so ATX12V v2.0 PSU models on the Intel list, and none of them were tested for the 240VA current limit conformance. My sources say that if these models had been tested, more than half would not conform to the 240VA current limit because they have only one 12V line.
In the last couple of months, my PS engineering sources report, Intel has verbally informed them that the 240VA limit has been removed. A single 12V line is now "officially" approved, never mind what ATX12V v2.2 specifies.
What does all this mean? Essentially, the only potential benefit of dual 12V lines is improved safety, and this is questioned by the engineers I spoke with. There are many downsides to dual 12V lines, including higher cost and the extra headache of ensuring adequate 12V current for all the components in complex, high power systems. For the consumer who is trying to make a choice among the myriad of PSUs available on the retail market today, the most practical approach regarding dual 12V lines and power capacity is to consider only the combined 12V current capacity. (It will certainly be interesting to see how Intel handles this issue in the next version of ATX12V.)
But you better read their site, as there is way more info there regarding PSU's then any other site I know of.