Computer randomly rebooting for no apparent reason

dudeman509 · Jan 24, 2015

Bit of an old computer, but it has been completely stable for the previous owner. Computer (motherboard/cpu) was transferred into a new case. Computer was given to me after a power surge took out my old build (apparently protector had developed a fault).

Build:
ASUS M3N78 Pro
Phenom 9500/stock AMD cooler
2x Crucial PC2-6400 2GB 6-6-6-18
2x Corsair PC2-6400 1GB 5-5-5-18
(memory is running @ 667 MHz due to AMD limitation - only 2 sticks can run @ full 800 MHz)
Geforce GTX 650
Crucial M500
Seagate SSHD
Ultra LS-500W power supply <- I am skeptical of this one
Windows 7 64-bit

Usually while Internet browsing or Youtubing (Google Chrome), computer will just randomly shut off for no apparent reason. No blue screen, no restart - just off. It turns right back on as if nothing happened. When I have had overheating problems with another computer, it would refuse to turn back on unless the power supply was turned off first, and then would display a warning in the BIOS when booting up again. This does NOT happen as any regular occurence and I can not induce it if I want to - completely of its own accord. Sometimes fine for a whole week, sometimes multiple times a night.

CPU heat sink re-pasted - idles @ 90F; never seen it go over 130F flat out @ 100% usage.
Northbridge re-pasted - this motherboard has just a giant heat sink. I briefly tried a northbridge cooler + paste; it crashed anyway.

Memtest x86 was run through 4 passes; did not see any errors.

I have stressed the machine for hours at a time with video conversion and playing games on top of that video conversion (100% CPU usage and heavy graphics card/northbridge activity) and it has been 100% stable.

I do not see any leaking capacitors on the motherboard. Power supply voltage looks stable as far as I can tell - system has been running for 4 hours with HW Monitor in the background and voltages are within .1V of 5 and 12V on each side.

Aside from a problem with the power supply, or possibly a RAM issue that's not showing up, what am I missing?

The whole build pulls under 200W full-tilt; most of the time around 100W. Could the power supply still be flaking out even though I am not seeing it in any monitoring programs?

spp85 · Jan 24, 2015

Try another PSU in your system to rule out the culprit is the PSU

roshansoza · Jan 24, 2015

i thks your power supply shoud replase for 450W and your windows sha to be format and reinstall again then your problen was ok

dudeman509 · Jan 24, 2015

spp85 :

10-4.

Thermaltake/430W or EVGA/500W?

dudeman509 · Jan 24, 2015

roshansoza :

Got another hard drive used as a backup with what is pretty much a clean install of Windows 7 and the latest version of drivers for this computer in a cabinet. Unhooked the other 2 hard drives and just ran off this one for a while. Still shut itself off.

Vic 40 · Jan 24, 2015

dudeman509 :

Think it's the psu too.Where are you looking? From these choices the evga.

Which monitoring programs used? Tried this?

Download hwinfo32,

http://www.hwinfo.com/download32.html

You can open hwinfo32,after that open the sensor window by marking sensors=V,after that click run,,then click at the bottom "Logging start" ,after that choose a name and place for the log. like Hwinfolog at your desktop.Leave it open and do game/stresstest or whatever you do until a crash or shutdown.The log will end at that point but will be saved.
You could look at the log yourself with either excel or libre office calc.

spp85 · Jan 24, 2015

dudeman509 :

Any working PSU that's available with you, friends etc to rule out a possible PSU failure. If the system works after changing the PSU, then you can buy a good quality PSU later....

dudeman509 · Jan 24, 2015

Vic 40 :

Yeah, I have been monitoring the hardware voltages in HWMonitor. Over 4 hours last night (where the system did NOT shut off), I didn't see any voltage fluctuations between .1V in either direction of 5V and 12V.

Tried to use a friends power supply from an old computer, but it was from a Dell, and didn't have the small 12V connector to the motherboard that I needed. All my other friends have laptops, unfortunately...

I'm going to pick that EVGA up from MicroCenter this morning and give that a shot. It may be several days before (or if) it happens again, but I'm hopeful that is is the PSU.

dudeman509 · Jan 24, 2015

Brand new power supply didn't fix it (Corsair 500W). Woke up from sleep mode and completely shut off about a minute or two after starting to use it - just light web surfing, a couple tabs in Chrome.

In my experience, bad RAM will blue screen, right?

Vic 40 · Jan 24, 2015

For ram could you set the timings manually to the specs of the 2x2 set.
Does the motherboard have the latest bios?

dudeman509 · Jan 24, 2015

Vic 40 :

Yes, latest version - released in 2010/2011 or something. I tried re-flashing the same version BIOS back to it just in case it was corrupt.

I have removed the 4 gig sticks for now, and am just running on the old 1 gig sticks that I know are good. It has bumped itself back to DDR2/800 running like this.

I also have a cheap USB3 card I added for an external hard drive. I'll remove that as well, just to test - I should think that would blue screen too, and it wasn't accessing the external at the time it crashed.

dudeman509 · Jan 24, 2015

Nope, did it again. Expansion cards replaced; 2x1 gig sticks removed; 2x2GB sticks installed.

Here goes...

At this point, just wondering if the motherboard is bad. Can't really be much else.

I've seen other complaints of the M3N78 series motherboards doing this, but never a follow-up or actual solution to what it was.

dudeman509 · Jan 24, 2015

Taking out the Corsair RAM seems to be working very well so far, even putting it to sleep several times. I have replaced the new PSU with my old one again for the time being - will update if it turns off again.

dudeman509 · Jan 24, 2015

Much longer this time, but did it again. That pretty much eliminates everything - I have done it without the graphics card and running integrated graphics.

Vic 40 · Jan 25, 2015

Maybe the motherboard get's a bit "worn out",you could try to add a bit voltage top the ram,like 0.5V on top (for ddr2 about 2.1 Max.) and see if that helps.Maybe add some to the northbridge too if this isn't enough.

You said that you changed back to the old psu,this also happens with the new one?

dudeman509 · Jan 25, 2015

Yes - just as frequently on the "new" PSU, if not even more.

I'll see what the BIOS allows for RAM voltages; I think you can do it in pretty small increments.

Vic 40 · Jan 25, 2015

dudeman509 :

I'd like to see what that gives.

dudeman509 · Jan 25, 2015

Prior to this EVERYTHING was in auto. I have no idea what I'm doing with voltages on AMD machines.

Vic 40 · Jan 25, 2015

2.080V for the memory should be enough,at 2.155 will it probably turn red meaning it being a bit too much.
When setting the NB Chipvoltage to manual is it set at a certain value,bump it one notch up if upping the ram voltage won't be enough.

See first how it does with only the ram voltage at 2.080V,if it doesn't help try the other voltage with one/two notches up.

You installed everything alright when changing the pc to another case? Like standoffs installed (correct) and such.

Maybe you can make such a log with hwinfo32 and upload it to dropbox,or similar (without to much crap),and post a link here.See if it gives something.

dudeman509 · Jan 25, 2015

Yeah, everything installed fine - I have actually taken the whole board out to install a Northbridge cooler, which didn't really seem to help matters at all - I just thought that the NB chip was getting pretty warm with only a heat sink on there. Nothing should be shorting it from underneath.

I have woken it up and done lots of web browsing off-and-on today, and it seems to be fine with only 2 sticks of RAM in there. Really wondering if this has done it or not.

dudeman509 · Jan 25, 2015

No luck playing around with any voltages; crashed it a couple times still.

Did the next best thing and went and bought a new motherboard/CPU this afternoon. HUGE improvement in stability/speed.

Vic 40 · Jan 26, 2015

Good luck with the new parts.

dudeman509 · Jul 19, 2016

Came across an old Phenom II from a friend recently.

Bad CPU was causing the cut-offs. No idea why - completely stable for days on end now.

Computer randomly rebooting for no apparent reason

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