I built a desktop computer a couple years back with the following specs:

  • CPU: Intel Core 2 Quad Q9300 Yorkfield 2.5GHz 6 MB L2 Cache LGA 775 95W Quad-Core Processor BX80580Q9300
  • Motherboard: EVGA 122-CK-NF68-T1 LGA 775 NVIDIA nForce 680i SLI ATX Intel Motherboard
  • Video Card: Two EVGA 256-P2-N758-TR GeForce 8600GT SCC 256 MB 128-bit GDDR3 PCI Express x16 SLI Supported Video Card
  • PSU: SeaSonic S12 Energy Plus SS-550HT 550W ATX12V V2.3 / EPS12V V2.91 SLI Certified CrossFire Ready 80 PLUS Certified Active PFC Power Supply
  • Memory: Two G.SKILL 4 GB (2 x 2 GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model F2-6400CL5D-4GBPQ

Since its inception, the machine has periodically locked up, the regularity having varied over the years from once a day to once a month. Typically, lockups happen once every few days.

By "lockup" I mean my computer just freezes. The screen locks up, I can't move the mouse. Hitting keys on my keyboard that normally turn LEDs on or off on the keyboard (such as Caps Lock) no longer turn the LEDs on or off. If there was music playing at the time of the lockup, noise keeps coming out of the speakers, but it's just the current frequency/note that plays indefinitely. There is no BSOD.

When such a lockup occurs I have to do a hard reboot by either turning off the computer or hitting the reset button.

I have the most recent version of the NVIDIA hardware drivers, and update them semi-regularly, but that hasn't seemed to help. I am currently using Windows 7 x64, but was previously using Windows Server 2003 x64 and having the same lockup issues.

My guess is that it's somehow video driver or motherboard related, but I don't know how to go about diagnosing this problem to narrow down which of the two is the culprit.

Additional information re: cooling Regarding cooling... I've not installed any after-market cooling systems aside from two regular fans I scavenged from an older computer. The fan atop the CPU is the one that shipped with it. One of the two scavenged fans I added it located at the bottom tower of the corner, in an attempt to create some airflow from front to back. The second fan is pointed directly at the two video cards.

SpeedFan installation and readings Per studiohack's suggestion, I installed SpeedFan, which provided the following temperature readings:

  • GPU: 63C
  • GPU: 65C
  • System: 76C
  • CPU: 64C
  • AUX: 36C
  • Core 0: 78C
  • Core 1: 76C
  • Core 2: 79C
  • Core 3: 79C

Update #3: Another Lockup :-( Well, I had another lockup last night. :-( SpeedFan reported the CPU temp at 38 C when it happened, and there was no spike in temperature leading up to the freeze.

One thing I notice is that the freeze seems more likely to happen if I am watching a video. In fact, of the last 5 freezes over the past month, 4 of them have been while watching a video on Flickr. Not necessarily the same video, but a video nevertheless. I don't know if this is just coincidence or if it means anything. (As an aside, each night before bedtime my 2 year old daughter sits on my lap and watches some home videos on Flickr and, in the last month, has learned the phrase, "Uh oh, computer broke.")

Update #4: MemTest86 and 3DMark06 Test Results:

Per suggestions in the comments, I ran the MemTest86 overnight and it cycled through the 8 GB of memory 5 times without error. I also ran the 3DMark06 test without a problem (see my scores at http://3dmark.com/3dm06/15163549).

So... what now? :-)

Any further suggestions on what to check? Is there some way to get a stack trace or something when the computer locks like that?


I have never did figure out the particular problems, but based on the suggestions here and elsewhere, I'm presuming it was a motherboard issue. In any event, I recently upgraded my system, buying a new motherbeard, PSU, CPU, and RAM, and that new rig has been working splendidly the past several weeks. I am using the same graphic cards as in the old setup, so I think it's safe to reason that they weren't the cause of the problem.

  • first word that comes to mind is heat... how are you keeping the system cool? Dec 10, 2010 at 17:32
  • @KronoS: I edited my question to include the cooling situation. Note that I am not using any CPU temperature monitoring software. Dec 10, 2010 at 17:37
  • 2
    You should install SpeedFan and let us know the temps...
    – studiohack
    Dec 10, 2010 at 17:40
  • @studiohack: Thanks for the suggestion - I downloaded and installed SpeedFan and edited my question to include these new readings. Are these temperature readings normal? Dec 10, 2010 at 18:05
  • 2
    @Scott Download 3dMark '06 & FurMark let it run for couple of hours. Report any crashes. If it does crash, use only 1 video card at a time
    – Sathyajith Bhat
    Dec 14, 2010 at 17:54

13 Answers 13


Judging by what you posted temp and cooling wise your computer is overheating and that's the first thing to rectify. 64 C on an idle load is not acceptable and isn't really preferred with a full load. I'm a little paranoid and freak out whenever my CPU get over 35, but really 50 should be your max on a load.

Invest in a good cooling solution for your system. A pretty decent system will only set you back 20 to 30 dollars. If you are looking for some help on what to look for take a look at this Tom's Hardware review of sub $40 cooling solutions.

Also you might want to enable your Blue Screen of Death (as terrible as that sounds) so that you can debug the problematic lockups. This is done by:

--> right clicking on "Computer" from the start menu

--> Select "Properties"

--> Select "Advanced System Settings"

--> Select the "Advanced" Tab

--> Select the "Startup and Recovery"

--> Make sure that "Write an event to the system log" is enabled.

Sometimes there are cleaners that automatically stop BSOD's from recording (Advanced System Care) and you might want to look into preventing that. Once you've checked this issue, then I suggest using NirSoft's BlueScreenView to view the crash details/debug related issues.

Finally, I would check and recheck your PC and ALL of your connections. I actually had a similar situation and found out that one of the internal motherboard USB cables was incorrectly connected, thus causing issues.


I have put together some questions for general troubleshooting and diagnosis of crashes or freezes. Please refer to them as well, as they may also help you in your search for the issue.

  • @KronoS: Do you have any recommended cooling systems you care to share? Dec 10, 2010 at 18:11
  • @ScottMitchell... updated answer. I highly recommend that you do your research though as each Super User's situation is different. Dec 10, 2010 at 18:14
  • 3
    @ScottMitchell I'd recommend you change the thermal interface material (TIM aka thermal paste) first before adding any external cooling. Also, check for dust coating on fans / grills / vents and clear them off using a blast of compressed air can.
    – Sathyajith Bhat
    Dec 10, 2010 at 21:36
  • @Sathya: Thank you for the suggestion. I cracked the case last week and had the computer run for a day with an open case and the temps dropped into the 40s. This morning I inspected the CPU's existing cooling system and noticed a lot of dust covering the grills underneath the fan, so I cleaned those up. I put the case back on and we'll see if the temps stay low and if that helps prevent future freeze ups. (If so, I'll mark this as the answer...) Dec 13, 2010 at 16:54
  • @Scott Ah glad to hear, do keep us updated.
    – Sathyajith Bhat
    Dec 13, 2010 at 17:02

Hard system freezes (where you can't use hotkeys like CTRL+ALT+DEL) are caused by hanging drivers,
so you will have to either replace the device or update the driver. Troubleshooting can be done:

  1. Download the setup from Windows Performance Analysis Tools for your Windows version.
  2. Install the software on your system.
  3. Open a command prompt as administrator, and copy paste the next command:

    xperf -start perf!GeneralProfiles.InBuffer && timeout -1 && xperf -stop perf!GeneralProfiles.InBuffer myTrace.etl
  4. Press ENTER once to start the command, now you will have to wait till your system hangs.
    You can do whatever you want to. Please no heavy activity like gaming or private things...

  5. Right after your system stops hanging you go to the console and press ENTER.
  6. After waiting some time a log file myTrace.etl will be produced, compress this to a zip file.
  7. Put this compressed version of the file somewhere online (perhaps 2shared).
  8. Share the link here, I will do an attempt to find and show you the cause of your problem.

If it has been a couple of years since the computer was built, then a thorough cleaning would be a good course of action. Remove all dust from the fans, heat sinks, boards and corners. The most important parts are the CPU heat sinks and fans. Compressed air is good for this purpose, but a vacuum cleaner may be healthier in the long run. Doing this thoroughly will greatly reduce the ventilation and reduce heat.

Heat should not have been an issue with a new computer, unless it is kept in a very warm and poorly ventilated room (or cabinet). CPU manufactures anticipate their products being used in varying conditions and even the stock heat sink and fan are made to enable the product to work under most circumstances.

Since you've had the issues since you built it i tend to lean towards a failure in one of the components. Based on the issues described i am leaning towards a faulty motherboard, just based on my own experience.

  • 1
    As I noted in my question, this problem of freezing up has been occurring with some regularity since I built the computer. Sadly, it is not a recent occurrence. Dec 10, 2010 at 18:50
  • correct. which is why i lean towards a faulty piece of equipment rather than heat, as heat should not have been an issue when you first built it (unless where you keep the computer is very warm to start with)
    – Xantec
    Dec 10, 2010 at 20:07
  • Heat could have been an issue when the system was built. We once received a dual processor workstation from a major manufacturer with the processor fans connected to the other processor's mother board fan pins. ... But not likely the problem in this case.
    – Mike Chess
    Dec 16, 2010 at 5:10

I went through this process last year.

First thing is to determine if it's hardware or software. That means running two different OSes on it. In my case, my primary installation was linux, and it was freezing at random - similar to what you describe. Sometimes every 5 minutes, other times it would go for several days.

I eventually installed Windows on it, which experienced the same problems. When I rebooted, and it hung during the post, I returned the MB and have not had a problem since.

As part of the debugging process, I also tried different video drivers - the generic, non-accelerated drivers did not freeze as often. I also installed temp. monitoring utilities, and reviewed logs to see if there was anything common happening before the freeze. Since it was hardware, and apparently random, I never did find any way to reliably cause the problem, but that should be your goal.

  • I'm not exactly sure what you are suggesting here? Dec 10, 2010 at 17:54
  • If it's a problem with the hardware, the problem will be present regardless of the OS. If it only show up with one OS, and not another, then it's most likely software.
    – chris
    Dec 12, 2010 at 19:09
  • 1
    @chris: The problem has been around since I built the computer. Initially I was using Windows Server 2003, later I upgraded to Windows 7. With both OSes I have experienced these freezes/lockups. Dec 14, 2010 at 17:36
  • @Scott - Are you monitoring the GPU temps as well? If multiple OSes experience the same problem, I'd lean towards hardware, although I'd guess that both are using the same video driver. Have you tried removing one of the video cards, and seeing if you can narrow it down to a specific card?
    – chris
    Dec 14, 2010 at 17:47
  • 1
    Well, if you make the assumption that it's not the video cards, then that leaves memory, motherboard, or software. If you rule out the software due to seeing the problem with both Win7 and Win2003 (which I would not) that leaves memory or MB. Can you swap out the RAM?
    – chris
    Dec 14, 2010 at 22:02

I would suspect the power supply first. Try replacing it with a higher power unit and see if things become more stable. It may be that the voltage rails are drooping a bit under load, which explains why it's showing up more frequently with video playing.

To test this theory, you'll need an accurate voltmeter and some basic electrical skills, but given how useful a spare power supply is I would be tempted to just swap it and see.


Based on your update # 3 and a lockup at 38C, mobo/cpu heat is not the root cause. Assuming that you only have the video cards added and no other additional cards (i once had a nic do this!), I make these recommendations in order of what I believe is most likely the cause:

  • Replace the video cards with a different known good card to troubleshoot. Buy one, borrow one--whatever. If that doesn't fix, then on to the next bullet.

  • You mentioned updating the video card driver, but none else. Make sure all possible drivers are indeed current. I had a nic card do this one time and all I had to do to fix was update the driver.

  • If you indeed do not have any other add on cards (if you do, remove them now), disable all optional equipment in the bios. By that I mean your onboard sound, lan and pull out any usb items. Then, see if it goes away.

I'll go out on a limb and say I'm 90% certain it's going to be fixed by doing bullet #1.


Probably a video card problem, replaced lots of 8600GTs (G84). It was a big flop on NVIDIA's side, esp. in laptop(8x00M) series.

GPU temp of 65°C seems too high if it was idle.

Run five minute burn-in test with Furmark; if it hangs - video card is culprit.

Problems https://en.wikipedia.org/wiki/GeForce_8_Series#Problems

Furmark http://www.ozone3d.net/benchmarks/fur/


It sounds like hardware or drivers are the issue here. Though I'd be leaning hardware since you've had two different OSes on the computer.

Working on that assumption then start with the easiest stuff. I saw that you ran Memtest and while that is great it doesn't necessarily rules out memory as being suspect. So try the following: take out all but one stick of memory and see if you get a lockup. If it runs fine for a while then put one more in and so on until you get the problem again. If it still locks up then try a different stick in a different slot. If it is still locking up then move to other hardware components.

Some people mentioned trying to swap out your video card and I agree. Buy a cheap one or borrow one from a friend and try that. Do the same with a power supply. Your PSU seems like a decent one, but they do go bad and it is worth swapping out and seeing if that fixes your issue.

If all of this fails then I would say replace the motherboard. Especially since you said you've had the problem since you first got the computer.

One last thing to check just to be on the safe side. Do a chkdsk/SMART test on your hard drives. They are probably fine but worth checking anyway.


From your description it looks like the problem is on the motherboard. It could be that your northbridge has a problem (motherboard diagram). What I would check as well is the BIOS configuration for the clock generator and the CPU speed. (I don't know your motherboard but maybe it has some overclocking features.) Maybe the problems always happens when there is a high load and the CPU tries to run faster.


I'm going on a wing here and suggesting the culprit is a blown capacitor that is unable to supply an electrical charge to smooth current fluctuation errors. I'm guessing a significant enough fluctuation will cause the system to freeze but stay on.

Based on past experience I would pin the blame on a blown capacitor in your power supply unit (PSU) but I would suggest checking all the capacitors in your computer, in and around the motherboard, particularly around the north bridge. If you have been over-clocking, the motherboard is likely to have been fried. Though unlikely for any capacitors to have blown under heat sinks, that may also be a possibility.

If you do not find anything blown on the motherboard, I would warranty your PSU as some have a long warranty - mine 7 years - so don't open it up to inspect it unless you know you're out of warranty. A decent power supply may be fixable with the right tools if it's just a capacitor.


I've handled many situations like this, and the most common problem that I found with lockups or freezing was heat sink paste. Your fan can do whatever it wants to, but if an air gap between the heat sink and the CPU is allowed, the heat sink will not cool the air between the two. If that paste is too dried up or on places it is not supposed to be or not enough or not allowing a conductive heat connection between the processor and the sink, it will lock up because it is turning on a processor protection circuit in the processor itself. Do it five or six times till that problem goes away. It eventually will, or we will throw your processor away and send you a new one without even telling you. We do not want to replace your CPU. We do it 10 times before we do that.

  • 1
    I can believe that you might know what you’re talking about, but I can’t understand what you’re saying. Please edit your answer to clarify –– I’ve given you a start. For example: “Do it five or six times …” –– do what? “We do it 10 times …” –– do what, and who are “we”? Also, please clarify what you are saying that Sathya♦ didn’t already say in his comment on Dec 10, 2010 at 21:36. Jun 27, 2013 at 23:57

It may be a driver issue - whenever it is about to handle your video it will most likely crash (it may also make a weird noise) because your screen is freezing - the CPU may still work - in fact everything could be working - you may just not be able to see the results of your mouse/keyboard manipulations, because once your driver crashes there is nothing to handle the visual representations of inputs.

Potential Solution: Update the driver, if it started when you updated a driver revert to the previous driver, if your graphics card is old - try buying a new one - sometimes when old cards are patched with new drivers they might be buggy.

Overheating is really a problem only when your card working 110% of its manufactured power it can cause a crash but again IF only you boosted it very heavily.

  • Thats a guess, although a decent one. But it could also be power, an individual component failing, heat somewhere besides the CPU (GPU, Hard Drive) It could also just be a bad install. May 11, 2013 at 22:03

I agree with Nori about doing a SMART test. Use (the free edition) HDTune to copy in the SMART attributes. Also do a Error Scan. A single damaged sector can cause the problems you are describing. Overheating usually causes BSOD's and a forced reboot or shut down. Since it is "freezing", it sounds to me more like a hard drive issue (even though bad hard drives can cause BSOD's too).

Check the SMART status and make a note of the "Power On Hours Count" Data. If the count does not increment after a few hours, the SMART attributes are probably frozen and giving you a fake "OK" status.

Also check your windows System and Application event logs for errors.

(control pannel -> Administrative tools -> Computer management -> Event viewer)

Be sure to have all your important data backed up.

  • Disk problems almost always worsen over time, which is not the case from the description. Dec 21, 2010 at 15:26
  • @Flotsam Good point. A flaky hard drive would probably be dead after a few years. Perhaps a flaky RAID controller then. The event logs could still provide some good hints.
    – James T
    Dec 21, 2010 at 20:41
  • Not terrible advice but not on the spot for this configuration and described symptoms. May 5, 2013 at 20:16

Not the answer you're looking for? Browse other questions tagged or ask your own question.