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New homebuilt system randomly reboots

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Last response: in Systems
October 28, 2013 1:14:52 PM

Hello, I'm hoping that I can get some help with troubleshooting a computer that's randomly rebooting.

The computer will reboot with no warning at random times, when under stress or idling at the desktop.
I've run system file checker, antivirus, chkdsk, windows memory diagnostic and kept an eye on the temperatures. All these come back ok, files intact, no virus, memory passes, HDD fine and temps at around 50' under strain.
I have deselected automatic rebooting to try and get a BSoD error message but it comes up with a black screen instead (still has power though).
I have noticed some graphical bugs while playing games.

Is this likely to be a motherboard issue?
Since there are graphical bugs and a black screen instead of BSoD could this be a Graphics card issue? Can graphics cards even cause reboots?
Any help that you can give would be appreciated.

System Specs:
CPU AMD FX 6 core FX6300 Socket AM3+
GPU Sapphire Radeon HD 7870 2048MB PCIex16 3.0
MB Asus M5A97 R2.0 ATX chipset 970 socket AM3+
Memory Corsair 2x8GB DDR3-1866
Power Corsair HX850 Professional Series HX 850W

Thanks in advance for anyone's help

More about : homebuilt system randomly reboots

a b B Homebuilt system
October 28, 2013 1:19:56 PM

Check out your system logs (control panel - view event logs) and look for errors. There may be a trail to follow.
October 29, 2013 12:57:40 PM

I've been going through the event logs but most of them are about lack of internet connection, I'm a long way from the wireless router...
The only logs that look useful are:

Log Name: System
Source: Microsoft-Windows-Kernel-Power
Date: 25/10/2013 23:56:07
Event ID: 41
Task Category: (63)
Level: Critical
Keywords: (2)
Computer: Harlequin
The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly.
Event Xml:
<Event xmlns="">
<Provider Name="Microsoft-Windows-Kernel-Power" Guid="{331C3B3A-2005-44C2-AC5E-77220C37D6B4}" />
<TimeCreated SystemTime="2013-10-25T22:56:07.805637900Z" />
<Correlation />
<Execution ProcessID="4" ThreadID="8" />
<Security UserID="S-1-5-18" />
<Data Name="BugcheckCode">0</Data>
<Data Name="BugcheckParameter1">0x0</Data>
<Data Name="BugcheckParameter2">0x0</Data>
<Data Name="BugcheckParameter3">0x0</Data>
<Data Name="BugcheckParameter4">0x0</Data>
<Data Name="SleepInProgress">0</Data>
<Data Name="PowerButtonTimestamp">0</Data>
<Data Name="BootAppStatus">0</Data>

Having looked this up online it's basically saying that the computer shutdown for an unknown reason, not all that helpful.
I'm getting an ATX power supply checker to test that, may take a while to arrive.
Thanks for your suggestion, any other ideas?
Related resources
a b B Homebuilt system
October 29, 2013 1:38:08 PM

This looks like the error "bombs" the system (meaning the error condition is so critical, nothing is recorded as to the error).

It could be the power supply, but generally it would power down vs. just lock up like this.

Experience over the years from similar situations make this look like a bad motherboard and/or CPU.

To properly trouble shoot, you need another system with a similar build, and change parts until the problem goes away on one machine, then appears on the other.

The easiest tests would be to exchange video cards (if you have a spare), swap RAM (if you have a spare), then the PSU. If it is none of those 3, it would be confirmed as being the motherboard.

I had one system that occasionally just "died" after a PSU fried in it. The system ran another 4 years, before the problems became daily. Usually it would die about once a week or so.
October 29, 2013 3:10:12 PM

Sorry If I miss typed something but the system doesn't lock up.
It drops everything it's doing in an instant and reboots, the system is fine to use afterwards (until it reboots again) and I can't see any signs of power outage.
Unfortunately I don't have many components to troubleshoot with, would there be any other signs to look for depending on which component is bad?
a b B Homebuilt system
October 30, 2013 1:07:08 PM

Intermittent problems are very difficult to diagnose sometimes. It took 3 years before my motherboard finally started acting up enough to diagnose it. I would run Prime-95 on the mobo for 48 hours, no errors, and then it would go for 2-3 weeks before finally an error - but it may be another month before the next.

Video card, memory and/or motherboards are the most likely issues - it could be as simple as a dirty fan that isn't spinning - but generally you would be given a heat related shutdown in the event logs. There is probably a capacitor on one of the components that gets to a certain point and fails that is causing the issue.
October 30, 2013 1:45:00 PM

I'm buying a few spare parts to try and track this down, I'll just have to wait for them to arrive
November 2, 2013 5:54:48 PM

The spare parts have arrived and i'm in the process of stripping the system and testing each bit.
Since the problem is randomly timed reboots it may take a while to go through each part, add to that it took a week before the problem showed up in the first place. I may find the faulty part, replace it and find this happens again a week later... fun stuff !
a b B Homebuilt system
November 4, 2013 7:30:24 AM

Like I mentioned earlier - it took 4 years of random reboots and lock ups before the mobo finally died. I hope it doesn't take that long for you.
November 4, 2013 11:35:18 PM

4 years of reboots doesn't sound like fun...
I've used the extra parts I bought and striped the system down then slowly tested it one piece at a time. The whole thing works.
It took a week for this problem to occur, so maybe it'll happen again next week or maybe I didn't attach a component properly first time.
Oh well I guess I'll just have to keep an eye on it.
Thanks for your help and suggestions.

White Lancer