Mind Boggling PC rebooting problem

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LazerFazer

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Hi everyone,

Let me start by saying I usually debug my own hardware problems, but this one has me completely stumped. So here's the story:

Last week I passed my old motherboard, CPU, RAM, GPU, and PSU to my brother, and ever since he's been experiencing random rebooting while gaming (random in the sense that sometimes it's immediately after starting a game, while other times it's after 30+ minutes). We've tested the CPU (using Prime95), GPU (Using MSI Kombustor), RAM (Using MemTest 86+ bootable flash disk), and stressed the PSU (using MSI Kombustor and Prime95 simultaneously). Nothing failed any of the tests, nor did the PC reboot at any stage of the tests. We've also updated all the drivers and installed all applicable patches/updates. We've even swapped the RAM modules around without any success.

The strange thing is it's COMPLETELY random. For example, yesterday he managed to game the entire day without having any problems, but the day before and today it's been rebooting.

I'm at a complete loss as to what the problem may be, so I'm hoping one of you will be able to help. His system specs are as follows:

CPU: Intel Xeon E3110 2x3GHz (stock clocks)

GPU: NVidia GeForce 8800GT (With latest drivers)

RAM: 2x2GB + 2x1GB DDR2-800

Motherboard: Gigabyte GA-X38-DQ6

HDD: Samsung HD204UI (2TB SATA-300)

PSU: Huntkey 500W (shouldn't be a problem, seeing as it was used with the exact same components before without problems)

Thanks for your assistance.

Edits:

No blue screens, even though the option to automatically restart is turned off.

I doubt the CPU is overheating, seeing as even running Prime95 for a fairly long time doesn't heat it anywhere close to the critical temperature (I think the highest it got was <60C). Also, the problems happened at two completely different locations: At home and at a LAN, with completely different mains power supplies.

Something I forgot to mention earlier: When the PC reboots it's actually more like a hard reboot, where the PC turns off momentarily then back on again.

The system is a fresh install, just installed it the day we transferred the equipment because he got a new HDD to go with the rest of the system.

The BIOS option for "AC Back Function" is set to "Soft-Off" which is defined as "Always in off state when AC back".

Although it's seeming more and more likely, I can't understand how the PSU would be failing, seeing as a day before the failures started it was running fine in my system with the exact same hardware, except with an HD6870 instead of the 8800GT.

I'll try running PCMARK and 3DMARK as well to replicate the problem in a non-game environment. Results will be up in a few hours.
 
Last edited:
Do you get any blue screen?

Try switching that option off to restart the system on failure so that you can see if there is any blue screen.
 
It could be that the CPU is overheating? A pc usually reboots automatically when it reaches a certian temperature.

Also, maybe theres something wrong with the PSU?

EDIT: Is it possible that theres something wrong with the wall socket where you plug in the PSU? Maybe an occasional dip in power and it restarts.
 
Thanks for the replies.

@stevovo
No blue screens, even though the option to automatically restart is turned off.

@Elite Override
I doubt the CPU is overheating, seeing as even running Prime95 for a fairly long time doesn't heat it anywhere close to the critical temperature (I think the highest it got was <60C). Also, the problems happened at two completely different locations: At home and at a LAN, with completely different mains power supplies.

Something I forgot to mention earlier: When the PC reboots it's actually more like a hard reboot, where the PC turns off momentarily then back on again.
 
Reload the system and work from there.

Sounds like an overheating problem but if you stressed it and cannot get the system to shut down then give it a fresh install.

Try run pcmark as well and see what happens. 3dmark would also be a good one to run.

You may find testing one piece of hardware at a time is not giving you the problem.
 
Last edited:
LazerFazer said:
Thanks for the replies.
Also, the problems happened at two completely different locations: At home and at a LAN, with completely different mains power supplies.

Something I forgot to mention earlier: When the PC reboots it's actually more like a hard reboot, where the PC turns off momentarily then back on again.
Click to expand...

Go check in the BIOS, it has a setting: If the power goes down without warning, it will automatically switch back on when power returns. Make sure it is off, then you'll know whether it restarts or shuts down fully.
 
Elite Override said:
Go check in the BIOS, it has a setting: If the power goes down without warning, it will automatically switch back on when power returns. Make sure it is off, then you'll know whether it restarts or shuts down fully.
Click to expand...

+1, I'm also leaning towards the psu failing if it's not the above.
 
The system is a fresh install, just installed it the day we transferred the equipment because he got a new HDD to go with the rest of the system.

The BIOS option for "AC Back Function" is set to "Soft-Off" which is defined as "Always in off state when AC back".

Although it's seeming more and more likely, I can't understand how the PSU would be failing, seeing as a day before the failures started it was running fine in my system with the exact same hardware, except with an HD6870 instead of the 8800GT.

I'll try running PCMARK and 3DMARK as well to replicate the problem in a non-game environment. Results will be up in a few hours.
 
LazerFazer said:
The system is a fresh install, just installed it the day we transferred the equipment because he got a new HDD to go with the rest of the system.

The BIOS option for "AC Back Function" is set to "Soft-Off" which is defined as "Always in off state when AC back".

Although it's seeming more and more likely, I can't understand how the PSU would be failing, seeing as a day before the failures started it was running fine in my system with the exact same hardware, except with an HD6870 instead of the 8800GT.

I'll try running PCMARK and 3DMARK as well to replicate the problem in a non-game environment. Results will be up in a few hours.
Click to expand...

I always try to mention this last, but are you certain there are no backdoors or other malware on the system?
 
Ja, random reboots are a pain in the ass.

It doesn't sound like a driver issue.

It does sound like a power issue.

Have a look at the motherboard and see if there are any swollen capacitors. They're pretty big and are around the CPU and where the power plugs into the motherboard. A good cap has a flat top and you can clearly see the cross indent in the metal. We've a few motherboards like that at work and ended up stripping others to get one working again.

Sometimes cleaning the CPU, putting new paste on can make a difference. Also giving the heatsink a clean. This does relate to overheating though - which you don't think is a problem.

If it's the power supply, try and disconnect as many peripherals as you can. Like extra HDDs and DVD drives. I stand to be corrected, but I'd imagine that while gaming you're going to use a bit more power than just sending an e-mail.

Have you tried using a different GPU or the on board GPU?


Sent from the MyBroadband iPhone App
 
Had similar issue with a clients server, eventually swopped out the PSU (Even though it ran well under tests) & server worked fine.
 
I would agree with Wesoli and actually repeat his steps twice. If your still not successful then you need to accept serious hardware failure, it can happen.
 
During the ''transplant'': did you reseat the RAM & CPU too? It could be that one or both moved a little during the ''manhandling'' process. Also when reseating the CPU, was the thermal paste replaced with fresh paste?

The internal fans & airflow in the ''new'' chassis - are there enough fans, are they plugged in(easy to overlook when in a hurry), are they working?
 
From the sounds of it, either your PSU or Wall Socket are at fault. Try using your previous GFX card and, if that makes no impact, an alternate HDD to eliminate potential causations. I also agree with Venomous that if the RAM or CPU was removed, ensure they are seated correctly and are in the same configuration as before.
 
I would also think its PSU.

But if you installed it into a different chassis, is there a chance that you could be picking up a short.
If you have the patience you can always run the system outside of the chassis to see if symptoms persists.
 
Perhaps even the power cable itself? You say it can't be the socket as it happened in 2 different locations, so I'd assume it's the power cable itself or the PSU.

Having said that, there could also be a wire shorting in the case itself. Built a pc for someone and it had the exact same symptoms as there was a front panel cable which had a slice in it and it kept hard restarting the pc. We tried it in a different case and all was well so we fixed the wire and voila
 
As the general consensus goes, overheating is the most likely cause. Checking capacitors is a good suggestion too, seen this happen once. I also concur with the thermal paste issue.
 
Intriguing.

I reckon the problem is either:
  • GFX & PSU don't jive
  • Its the case

Start troubleshooting the GFX & PSU first. Swap the gfxs back & see if that helps. If that doesn't fly put the 8800 back in. If you've got access to another PSU then swap that.

If all that fails: Find a wood table remove the entire rig & rebuild it on the table. Carefully. Memorize the pins for the reset & power on/off. Do not connect them to the case. Instead use a screwdriver to (very carefully) short the power on/off once to power the PC on.

The tricky bit is that if that works you don't know whether it really is the case or a cooling issue, so you might want to test a portable fan + open case first. I doubt this is a cooling issue though...doesn't feel right.

LazerFazer said:
yesterday he managed to game the entire day without having any problems, but the day before and today it's been rebooting.
Click to expand...
I bet that correlates with the weather report for your location on those days. Specifically humidity.
 
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