My computer freezes at random intervals when I'm using it the screen will freeze and the light on my G5 mouse and keyboard will turn off, and I'll have to restart the computer. This happens less when I'm surfing the net, and more when I'm playing a game, for example i only got to the loading screen on L4D and it froze. I've never had the computer not freeze at some point when I've played a game, which usually takes 15 minutes or less I've run memtest on each stick of ram individually, and they both passed. I recently replaced my 8800 GTX with a 9800 GT because the former broke(my fault), and I've reformatted my computer 5 times this week, with the problem persisting, any ideas on whats wrong? Also, when I leave the computer off for an extended period of time, like overnight, the first time I turn it on, the computer will not post, when i push the reset button, it will post and starts up normally

Case: 3D Aurora 570
Mobo: Gigabyte GA-P35C-DS3R
CPU: Intel Core 2 Quad Q6600, 2.4ghz
Ram: Corsair 2gb PC6400 5-5-5-12
Graphics: XFX 9800 GT
HD: Seagate barracuda 1.5TB
Pwr: Antec True Power Trio 650 Watts
Screen: 2 Samsung SyncMaster 204BW

Is your computer at all overclocked? I had a very similar issue when my PD was overclocked to 3.5 by only upping the FSB, only it did not freeze as frequently as yours. Downclocking the cpu to 3.3 ghz completely eradicated the problem. Does your hard drive activity light on your case also turn off? Also the no-post could be another sign of cpu instability.

I don't overclock my PC at all, the hd activity light does turn off as well when the computer crashes, but I checked Core Temp when the computer crashed and the temps were only around 50 C so the CPU's not overheating, but I've noticed that even when my computers at idle and I'm only surfing the net, the memory is at 52% which I see from System Monitor which is an app from google desktop (but I don't know how reliable the information that this reading is).

You are using vista, right? If so, nothing is unusual about the ram usage, as vista is quite a ram hog. Also, you would not need high temperatures for your CPU to be unstable. When my computer was crashing, my CPU was at 46 or so. Do you have another computer you could test the CPU in, or another CPU to test in your computer? If so, go ahead and do that.

I use XP and no, i dont have another CPU, sorry

That is a massive amount of ram for so to be using while you are just web surfing. From all the symptoms, I would say you hAd some sort of malware, but you said it still occured after you reformatted. Has this always happene to your computer, or did it just start?

I think its been going on for a while

Try downloading and running Prime95. It tests your CPU stability. You should be able to find it with a search.

here are the results:
FATAL ERROR: Rounding was 0.5, expected less than 0.4
Hardware failure detected, consult stress.txt file.
FATAL ERROR: Rounding was 0.5, expected less than 0.4
Hardware failure detected, consult stress.txt file.
FATAL ERROR: Rounding was 1, expected less than 0.4
Hardware failure detected, consult stress.txt file.
FATAL ERROR: Rounding was 0.5, expected less than 0.4
Hardware failure detected, consult stress.txt file.
these are for the 4 cores of my cpu, I thought that my computer would crash from this test, but instead, it BSOD-ed less than 5 minutes after the test, and the test took less than 15 minutes to... fail

After your fresh install, did you install all the latest drivers for your chipset and video card, did you apply the latest updates and service packs from Windows Update in Custom mode.

Did you allow Windows Update to update your video card's driver?

Your power supply is a decent one but we are going to have to make sure it has not failed.

We are going to check the actual voltages supplied by your power supply in the next step.

EDIT: just re-read your post and have other concerns, do you have the latest BIOS for the motherboard?
What are the settings in the BIOS for your RAM as in Voltage, speed and timing?

Read the prime95 stress.txt file for more info. I would almost certainly say it is a CPU problem, so if you have it under warranty you should definitely get it replaced.

That board supports both DDRII and DDRIII, have seen issues with BIOS values with this board.

I need to read the thread again.

What I'm saying is before CPU replacement, we need to and should check for the latest BIOS, it's values and the latest chipset drivers.

There is a BIOS F12e dated 2008/11/17 and few before that with some important updates.

Q6600 should be supported by most boards out of the box, but with computer systems and so many different configuration and settings, one can never know.

I personally don't trust any tests including memtest, HDD tests, and burnin tests, unless I'm %100 sure the hardware and power is OK as well as BIOS, drivers and patches are the latest.

If the +5V is failing, there will be data corruption, USB device problems, if the +3.3V is bellow 3.14V, the video card suffers, this also affects the CPU even though it uses the +12V rails. Then what combination of wires in case of multi +12V rails has been tried and used. Antec power supply as decent as they are and as much as I like their cases and power supplies, are not internally made by Antec and do not use the highest quality capacitors.

May be vuga419 is sure of his hardware and software, in which case any test can be taken seriously.

then we have the following which makes me want to try another drive just to see.
Please note the link no longer goes to that thread!

I have interest in this thread just because of the motherboard and the Seagate 1.5TB, I'll check it's progress for my information.

Hope you guys get it working soon, it's a good system..

Good point about the psu, Sharam. @Vuga419: You can download the CPUID hardware monitor to check your system's voltages, in case something is wrong with them. Try checking your voltages while prime95 is running. Do you happen to have an extra hard drive, in case it is a problem caused by the drive?

I do have an extra drive, but more importantly, I updated my BIOS, as you suggested, and now the computer starts up, but will not POST, nothing shows up on the screen, and all I see is my fans spinning. I've flashed the BIOS, but that didnt work. Now I'm stuck...

Have a look here: Tutorial: No POST (Power On Self Test)

You did get the right BIOS image file, right? have to ask.
So, you did not get a chance to get in Setup and load the defaults I guess?
Have you tried to reset the CMOS using the jumper or by removing the battery for a minute or so with the power supply disconnected from the outlet and any other power source to the motherboard as in VGA cable with the monitors on, RJ45 cable from the router and such.

I haven't checked your RAM's voltage requirements, if it is more than the default motherboard settings, you might need to try and boot with one stick or get a 1.8V DDRII and try.

I would also, check the manual quickly page by page for the jumpers on the motherboard with close attention to the DDRII and DDRIII settings.

Thanks kimsland, I was looking for that about an hour ago for another thread and searched every where but the guide and tutorial, I though it would be in the hardware section!

I downloaded @BIOS and updated it that way, not sure if that was the right move to make, I did flash the BIOS for over 30 minutes and still, nothing

BIOS flash should not take more than a minute or so if that. I had instructions waiting with my first reply but you weren't around.

What do you mean by:

Can you explain the steps you took in detail?