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Random PC shutdowns. Cause unknown

My PC is almost 3 years old and runs fine but has suddenly started to have random shutdowns for seemingly no apparent reason. It shutdowns when I'm just doing something like some browsing will several tabs open so it's not only when the system is under load. The system temps are normal, I can see them on rainmeter and on logitech lcd display. There are no sudden spikes in cpu or high usage of any components when it happens. The shutdown is instant and there is no blue screen crash or anything like that.

System specs:
Windows 7 64 bit
Intel i5-3570k
Asus Maximus V Gene Z77 Motherboard
EVGA GTX 660 ti FTW+ 3GB
2 x 8GB Corsair Vengeance DDR3 1600Mhz
Corsair CX750 750 Watt Power Supply
TP-Link Wifi adapter pcie card
1 SSD
2 HDD

Probably not worth noting but It's plugged into a probably more than 6 years old surge protector hub(maybe this can cause less clean power?) and the shutdowns started to randomly occur around the same timeframe that I installed f.lux .
It was overclocked a few months ago to 4.2ghz with offset voltage +0.015v and this was tested to be stable and I've been gaming with it. Since the random shutdowns I put everything back to default settings except the RAM in XMP mode with 1600Mhz, shutdowns still occur. Bitdefender scans shows no virus results.

I'm trying to isolate if it's a hardware or software problem and as I type I'm using the PC on a linux live usb but there hasn't been any random shutdowns yet. This may suggest a software problem but I don't think this is a very effective method for testing. Any ideas what might be causing the problem?
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  1. Best answer
    My first suspect is the PSU as the CX series are notorious for this problem. What happens is the cheap secondary capacitors age and start to fail when this happens the PSU will start shutting down seen it happen randomly and/or under load.
  2. here's a couple of things you can do:
    Plug straight into power source (surge protector may be on the fritz)
    Run MEMtest to see if there's any errors with your RAM
    Disable overclocking

    Can you describe the situation, as in is it a Blue Screen? Does the computer just shut off? Does Blue Screen and then restart in a loop? Overheating maybe causing shutdowns?
  3. bignastyid said:
    My first suspect is the PSU as the CX series are notorious for this problem. What happens is the cheap secondary capacitors age and start to fail when this happens the PSU will start shutting down seen it happen randomly and/or under load.

    This is also my first suspect but I still haven't been able to determine if it's hardware because ubuntu is running fine so far(Might do a stress test on ubuntu). The Power supply has a three year warranty and I still have a little over 3 months left on that so I should be covered if it's a power supply problem.
  4. As said those CX psu's have a bad reputation. Seems very likely it's the problem but the only way to be sure is by changing it.
  5. PCBuilderProbs said:
    here's a couple of things you can do:
    Plug straight into power source (surge protector may be on the fritz)
    Run MEMtest to see if there's any errors with your RAM
    Will do.
    PCBuilderProbs said:

    Can you describe the situation, as in is it a Blue Screen? Does the computer just shut off? Does Blue Screen and then restart in a loop? Overheating maybe causing shutdowns?

    If you read all of my post you would already have most of those those answers. Instant shutdown, no lag, hang, freeze or blue screen. CPU has been restored to stock clock. All temperatures are normal.
    Yes, It restarts in a loop straight after shutdown. It goes to the black screen asking you want to start windows normally or start in safe mode. After rebooting there is no windows error messages or logs.
  6. I did read it btw. If it's an instant shutdown that's usually caused by overheating or a power issue. You've disproved the overheating theory at this point so it's definitely a power issue, as an issue with the RAM would've caused a Blue Screen rather than a full-on shutdown.

    Again, try plugging your PC directly into an electric source (bypassing the surge protector, as you said it's old) to see if that'll solve the problem. If this doesn't fix the problem then it's a power supply issue.

    Btw, most likely the reason your PC isn't crashing with Linux at the moment is because it uses almost no resources in the background, the OS is built around being light and open-sourced. It makes sense that your PC would crash using Windows with all of the background processes.
  7. PCBuilderProbs said:
    I did read it btw. If it's an instant shutdown that's usually caused by overheating or a power issue. You've disproved the overheating theory at this point so it's definitely a power issue, as an issue with the RAM would've caused a Blue Screen rather than a full-on shutdown.

    Again, try plugging your PC directly into an electric source (bypassing the surge protector, as you said it's old) to see if that'll solve the problem. If this doesn't fix the problem then it's a power supply issue.

    Btw, most likely the reason your PC isn't crashing with Linux at the moment is because it uses almost no resources in the background, the OS is built around being light and open-sourced. It makes sense that your PC would crash using Windows with all of the background processes.


    Ok, thanks. I'll get to doing some testing then and report back here later on my findings. Thanks for the help everyone.
  8. Yesterday at 10 pm I suddenly had a system crash without any hiccups prior to it happening. Two hours later my friends computer crashed and his Windows files went corrupt or something. Now, at 7pm today just as I got on my PC (about 10 mins ago) I got a blue screen.

    Maybe it has something to do with a recent windows update that doesn't mix well with some kind of software or files that we happen to have on our PCs, or it could be some big virus spinning off.

    But it's most likely just a coincidence (who doesn't like drama though).
  9. Ross11 said:
    Ok, thanks. I'll get to doing some testing then and report back here later on my findings.
    Helpful is to first discuss what turns off power. A power controller. It is another component of the power 'system'. Even a PSU powers on or off only in response to commands from a power controller. Even CPU and memory can only operate when this power controller permits it.

    Everyone is saying 'try this' or 'maybe it is that'. Instead, get numbers so that the next reply can say exactly what is defective. And then recommend specific solutions - without speculation. That means a digital meter, some requested instructions, and minutes of labor. Numbers from six wires make possible replies from the fewer who actually know this stuff.

    That is what they say in the TV show CSI: "follow the evidence". Your other alternative is shotgunning. Keep replacing good parts until something works. Anyone, including yourself, can select what is best to replace next. Those are your only two alternatives other than to take it to the shop.
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