Solved Computer shuts off randomly

April 22, 2012 at 15:49:02
Specs: Windows 7, i7 / 12gig

My computer is shutting off randomly. It is a complete, no warning shut down. No BSOD, no visual clues at all. The computer then will power itself on after a short time. It will shut down in low performance situations, and I can't seem to consistently reproduce the shutdown. I've had the computer on for well over an hour now, but it shut off after 5 mins the time before.

I've checked the CPU temp logs and they are fine (40C max). I can't find a program to log other temperatures for free so I just have CPU info.

I have a relatively new 850W Corsair power supply, which should be plenty of power. I don't have a psu tester, or a spare psu, so I can't test it (suggestions?)

What's the next step in diagnosing this problem?

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✔ Best Answer
April 24, 2012 at 15:49:03

Okay, your ram should run fine at 1.5v no need for a voltage bump. For testing purposes, please run your ram in dual channel. Just leave one out for now.

Update your BIOS

April 22, 2012 at 15:57:12

Well the first thing I would do is to check the windows system log and see if there is anything strange in there.

So after the system shuts down, can you turn it right back on? If no. It sounds like there is a power problem with either the board or the power supply. You will have to test the setup with a different power supply.

Also those power supply testers only really work if the power supply is completely dead, not when there is a low amperage situation.

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April 22, 2012 at 16:20:29

Thanks for the quick reply. The logs don't tell me much. I get a critical error saying the system has rebooted without clearly shutting down, which is obvious, but the errors before that deal with Dhcp-client network address issues and I think quite unrelated.

When it powers down, it sits for some time and then powers up again after a short time (5-10 secs) without me doing anything. I've let it do that for the most part. I think I remember trying to press the power button while the power was off and it wouldn't respond. I will be sure to try the power button the next time it powers off to confirm.

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April 22, 2012 at 16:41:44

That's a hard cycle, most newer boards do that when the something changes, or it can not POST with BIOS settings. Most Asus MSI and Gigabyte boards do this. Is there an event log in your BIOS? That would help out.

I need a list of your hardware so I can check the compatibility. But if I was going to guess, I would say that you are running 2.0v ram at 1.8v. or there is some other failure with the memory.

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April 22, 2012 at 17:29:26

I can't seem to find the bios logs. I looked all over the bios UI and never saw a mention of logs or system events. Of course the ASUS page for my board is down so I can't look up if the feature even exists, which I assume it does.

It may well be that the memory voltage is not correct. This is my first scratch build and that possibility was unknown to me. Here is the list of components (i also have 2 other hard drives which aren't listed in it, but I don't have exact specs for them without opening the case).

-ASUS P8Z68 DELUXE/GEN3 LGA 1155 Intel Z68 with UEFI BIOS
-Intel Core i7-2600K Sandy Bridge 3.4GHz
-CORSAIR Vengeance 12GB (3 x 4GB) 240-Pin DDR3 SDRAM DDR3 1600
-CORSAIR Enthusiast Series CMPSU-850TX 850W Power Supply
-2 x SAPPHIRE 100312-3SR Radeon HD 6950
-90GB SATA III Internal Solid State Drive (SSD)

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April 22, 2012 at 17:40:26

haha, I have the P8Z68-V PRO /GEN3, 2700K and the same ram. But why do you only have 3 sticks? Did you upgrade from a socket 1366 board? If this is an older 3 channel kit then most likely the ram that you have is rated at 2.0v. Anyway, I found that my board didn't lock the correct SPD from the ram until I turned up the voltage on the ram Stock is 1.8v on my ram. I run my corsair at 1.9v This is safe to do.

I would remove one stick of ram from your system so that you run at dual channel, if you have 3 sticks installed you will only run at single channel rate.

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April 22, 2012 at 19:58:51

I like the setup; it give me some confidence to hear that you use the same stuff...means the research I did in the beginning was probably ok. I did originally have a different mobo with triple channel, and so I got a set of three, RMAed it and returned the processor for the 2600K, but kept the memory. Since I do a lot of photoshopping I want to keep the extra 4 gigs rather than the performance gain from matched memory.

I looked into it and I haven't been able to prove that having double/triple channel is significant anyway. I'd like to be shown otherwise if you have a link. Here's an article i found, but it is a bit older:

I'm not much of a hardware tuner, but in the bios I made the simple change from normal to performance mode and haven't had a shutdown yet. I'll keep the system on for a while and see if that stays true. I will try to change the memory voltage specifically tomorrow. Thanks for the help so far.

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April 22, 2012 at 20:27:02

No problem, let me know how it goes

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April 24, 2012 at 09:31:49

Well it is still shutting off, now it takes half a day or more though. I turned up the memory voltage from my system default at 15V, to 17V, and it said overclock failed, so I put it to 16V and it turns on. It did not fix the problem though, as my computer just shut off again after a few hours.

If i weren't afraid of randomly losing my design work, I'd accept a random shut down every few hours. As it is though, do you have any other suggestions?

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April 24, 2012 at 11:43:58

I wanted you to see what the voltage was on your ram, please take one of your sticks out of your computer and it should say the specs on the heatsink of the ram. Give me all the information on that ram.

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April 24, 2012 at 14:55:29

cleaned the computer a bit, checked plugs etc, and pulled a ram for inspection. The stick has a lot of numbers on it, the only ones that make sense to me are
clock: 1600mhz
voltage: 1.50V
timing i think: 9-9-9-24
which must be part/model numbers I guess.

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April 24, 2012 at 15:49:03
✔ Best Answer

Okay, your ram should run fine at 1.5v no need for a voltage bump. For testing purposes, please run your ram in dual channel. Just leave one out for now.

Update your BIOS

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April 24, 2012 at 19:38:20

I'm not trying to troll in here, but I recently had a similar experience with a system build. Turned out to be the 3-month old PSU from Thermaltake. RMA, never crashed again. I'd strongly recommend that before you play too much.

For what it's worth, my situation was quite similar. Computer would run fine for 8-10 hours, sometimes a day or two. Then would shut off. A few minutes later I could restart it, and it'd run for another couple of days. I ended up replacing the machine since the mobo and processor were 4 years old. Long story short, I tried to use the PSU in a different build, and wouldn't run, so I called Thermaltake and got a replacement unit, and never had another problem. I even rebuilt the old PC, and it's still running great too.

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April 24, 2012 at 20:21:42


Any help would be appreciated.

I too had a old P5B deluxe board that would just crash and it was the 500W antec power supply I was using, the power supply was not defective as I returned it and got the exact same one. The problem was that it did not have the proper amperage on one of the lines that was required by the board. I replaced it with a 750W thermaltake and never had a problem after that.

The problem does seem to be power related, and I was alluding to that earlier, I don't think the OP has tested the system with a different power supply yet. It could also be bad DC/DC converters on the mainboard, or failed capacitor. But this is new hardware, so it is less likely, but not out of the realm of possibilities.

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April 30, 2012 at 09:29:11

I have not had any problems since I updated my BIOS and installed all the motherboard software (I had just the drivers before).

I also re-did the wiring for my computer, as I had a lot of items on one bundle from the power supply and none on others, so i spread the load out more evenly (and made it more open for airflow somehow).

I think that updating the bios and software was the big thing. It returned everything to the stock settings so I'll be playing with overclocking slowly to see if I can reproduce the problem.

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February 21, 2013 at 06:34:17

Wow brave to update the BIOS on a pc that shuts itself off!

But nice work.

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March 20, 2013 at 12:03:34

i have the same issue but i can turn it right back on.

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March 20, 2013 at 12:17:09

For me, it was a bad connection between the motherboard and the power supply. When I shook it a bit, the power shut off, and would randomly happen otherwise. I didn't feel like replacing either, so I clipped the plug to the case in a way that it wouldn't move around and would stay on....been working for about 5 months now. I nearly had a duct tape fix on this one.

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March 20, 2013 at 20:14:06

Most likely a cheap power supply with poorly made connectors. I would have replaced the power supply. A cheap power supply can fail and take out other components as well as loose important data if when it craps out again.
Your choice of course.

You have to be a little bit crazy to keep you from going insane.

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March 21, 2013 at 05:13:03

Wow this is an old thread! You know those power supplies that don't quit make a good connection at the motherboard plug. I take a pick tool and ever so slightly bend the contacts in the molex connector, just to give a little more tension on them so they make a stronger connection. Works every time.

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