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I'm having some serious trouble diagnosing an issue that I've been having with a box I built a couple of months ago.

Here's the hardware: newegg wish list

After playing a game for 30-60 mins. The whole computer freezes (crashes?). It just stays stuck on the screen and is completely unresponsive. The only thing I can do is shut it down by holding the power button for a few seconds. I can replicate this more quickly by running Furmark for 3-5mins. Never a BSOD, just completely frozen.

Troubleshooting so far: I've had the issue under two separate XP installs and Win7 Pro with different driver version. (I have Arch Linux installed too. It's never had the problem, but I don't play games there.)

At first I assumed that it had to do with heat. I've monitored both the CPU and graphics card temps. I don't think it has anything to do with the CPU because I can run prime95 for at least a couple hours without any problems (haven't tried longer). And I've been able to cause it to freeze under Furmark with the GPU temps ranging from 59C to 80C, so it doesn't seem like heat there either.

Initially I did have the fourth core of the proc unlocked through the BIOS, but everything has since been returned to the stock defaults.

Finally I decided it must be a problem with the graphics card, so it's been RMA'd. In the meantime I'm using an ATI 6750. It has the same problem! So there probably wasn't anything wrong with the other card.

Does anyone have any ideas? Or suggestions? Let me know if I've left out any relevant details.

UPDATE 1: Memtest Passed
UPDATE 2: Computer doesn't freeze with the side of the case removed.

If it's not the graphics card, RAM, CPU, or HDD, and it does seem related to heat, that leaves only the motherboard. Does this kind of thing happen when a motherboard overheats? Is there a specific sensor that I can monitor?

UPDATE 3: I have been using the computer with the side of the case removed for a while and I've yet to have it freeze again. Although I can't use it that way forever. I'm fine with further upgrading the cooling system, but first I need to pinpoint what's overheating. Any suggestions? PLEASE?

UPDATE 4: A couple of weeks ago (before the new graphics card) I was able to take a picture of the temps after it froze. Although it is a camera phone pic, so it's not the best quality.

enter image description here

There are two things that I think might be relevant. First the VIN1 voltage shows a ridiculously large max. However, this doesn't happen every time it freezes and I've seen it report that number when it hasn't frozen. The other strange thing is that under the fans section, there are three fans that always appear right before it freezes. Under normal conditions the fans section only has one entry (CPUFANIN0).

UPDATE 5: I posted this in a comment "The case actually came with two 120mm fans, both of them pointing inward (intake). I replaced those fans with better ones. I also switched the rear fan to point out as an exhaust. Neither seemed to help."

share|improve this question
I would have thought it was thermal, too. Do you have problems with heavy processor load (say, Prime95)? One other thought is to install Wine on your Linux install and see if Furmark does the same thing like that. EDIT: Might be RAM, too (I don't trust Corsair, terrible failure rate from them), try something that throttles that to see if you can replicate it. – Shinrai Apr 29 '11 at 22:00
No problems under heavy processor load. Testing the memory does sound like a good idea, although I'm not sure if any of the symptoms actually point that way, do they? – jtmcn Apr 29 '11 at 23:07
@jtm - hard locks (incouding mouse, etc.) are usually RAM related. – Ƭᴇcʜιᴇ007 Apr 30 '11 at 0:18
possible duplicate of How to diagnose computer lockup/freezing problem – Ƭᴇcʜιᴇ007 Apr 30 '11 at 0:18
How are your case fans arranged? front fans should suck air in, rear fans should blow air out. – Simurr May 9 '11 at 20:11

Sounds like your GPU, CPU, hard drive and RAM are working properly, though you didn't post actual CPU temperatures.

Check your case fan setup. Make sure you are creating air flow, not just blowing air at stuff i.e. air flows into the case, through the case and then out of the case, not just cycling hot air around inside the case. Generally you want front case fans (if you have them) to suck air in and rear fans to blow air out (that includes and side or top case fans). However, if your case fans were setup incorrectly it should have showed in CPU and GPU temps, so probably not the problem (check it anyway).

WARNING WARRANTY MAY BE VOIDED - please make sure you are not voiding your warranty if you try the following advice and reapply thermal paste to your motherboard heatsinks. It may be best to send the motherboard back for replacement as overheating could have damaged something already.

Check your northbridge and southbridge heatsinks. They are the 2 heatsinks attached to the motherboard. One just below the CPU (northbridge) and the other next to the PCI slots (southbridge). I've had many new motherboards and GPU's come with little or no thermal grease and/or poor thermal pad placement.

You'll have to remove the motherboard to get the plastic clips off to reapply thermal paste. I recommend Arctic Silver 5, very nice stuff, though your Cooler Master heatsink appears to have come with some which would work just fine. It's basically the same process as applying thermal paste to the processor. Make sure both the heatsink and chip surfaces are clean before applying new thermal paste.

Edit -- Do you have another power supply you can test in your rig? Also make sure the power supply fan is working. Power supply issues usually result in power loss, but I've seen some weird stuff happen when the power supply isn't putting out enough power.

share|improve this answer
If the issue is related to the thermal paste on the stock heat sinks, is there something that would indicate that as the problem? Is there a nearby sensor that monitors anything relevant? – jtmcn May 10 '11 at 16:42
One of the motherboard sensors might be on the northbridge, though probably not. – Simurr May 11 '11 at 17:32
I don't have an extra PSU, although I'm building a second desktop soon, so I could pick one up now I suppose. (The fan does work though.) While it's probably a good idea to test it anyway, I had kind of ruled out a faulty power supply, because I would assume it would have the same issue with or without the side of the case removed. Does that make sense? – jtmcn May 11 '11 at 18:13
PSU fans generally suck air in and out the back of the PSU. With the case open it is sucking in colder air from outside of the case instead of the hotter air inside the case. – Simurr May 11 '11 at 18:40
Your problems still sound more like something overheating on the motherboard but it is possible it's cause by power fluctuations from an overheating PSU. Not likely, but worth testing if you have an extra PSU. – Simurr May 11 '11 at 18:49

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