Computer Turns Off Randomly

Hi all,

I put this little doozy together a few weeks ago:

C2D 6600
BFG 8800 GTS
4 GB Kingston value RAM
WD 79 GB Raptor + Caviar 320 GB
Vista Home Premium

It generally runs fast and stable. I've even completed Everest Ultimate tests on it. But, every once in awhile--like twice in the last two days--the damn thing just turns off. Like the power went out or something, it just shuts off while I'm working. The temps are all fine I think (MB 39c, CPU 33c, GPU 57c).

I'm new to building machines, so I have no idea where to even start diagnosing. Anyone have any ideas?

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  1. yeah what mpilchfamily said what powersupply do you have? are all the cables securely attached? try different programs to monitor your temp
    if its the blue screen theres many possiblities
  2. I've got a new Silverstone ST75F really good reviews. Is there anyway I can figure out if it really is the PSU? (Short of buying another one).

    I've been monitoring temps with Everest and the Asus PC Probe II and everything looks okay.
  3. Hm, your power supply seems good enough for sure. I would suggest maybe looking for Spyware/Adware, or like another post said, use another program to identify your temperatures [Speedfan maybe?].

    If not, I had this problem a couple days ago on one of my computers, and I re-installed Windows and it went perfectly.
  4. Just out of curiosity, what is your CPU voltage set to? I used to have the voltage on my X2 3800+ at 1.275v, and then I would get random shutoffs like yours. My system would just completely shut off, like someone had been holding the power button. It wasn't even load-dependent, could happen in a game or idling at the desktop.

    Then when I decided to try my hand at overclocking, I bumped the CPU voltage back up to 1.35v (stock for my CPU) for stability, and now my computer doesn't have that shutoff problem. I think it's because the CPU just wasn't getting enough juice. Problem's gone away.
  5. Just because a make and model of PSU seems good enough, that has nothing to do with a certain % failure rate any brand will have.

    This is a typical symptom of power problems, though it coud even be a loose power cable or small computer gnomes tossing bits of steel wool into your PCI slots. Examine whole system and take voltage readings. If there is any commonality to when the shutdowns occur such as % load, note that as well. You might go ahead and unplug all power connectors one at a time, inspect the contacts and mating socket contacts and plug back in securely.

    When it shuts off can you just press the case power button or do you have to do more like unplugging PSU from AC or flipping it's main cutoff switch on the back?
  6. Listen to I (not me... I :D ) Could be a power issue. Also, i own the same board and been reading about it on the asus forums for overclocking. They seem to have some issues with auto voltages being off after people flash to the latest bios (0602). The 1.2vHT should be manually set to 1.2 as default where it can be as high as 1.5 on auto.
    These boards are also memory sensitive, but mostly with mem problems they reboot and not shut down.
    Spy/adware and virus is also a possibility seeing as my brothers PC also just randomly shuts down out of the blue and is riddled with crap. Gonna have to work on that later though as i have my own problems to work out.
    Yuo see, unlike yours, my pc won't shutdown when i want it to :D but i'll fix it yet
  7. Guys, thanks a lot for the replies. I've actually been playing Oblivion for hours now (it's a holiday weekend :D ) and nothing has happened, knock on wood. So I don't think it's temps, since the hottest my mobo got was around 41c, and my CPU went up maybe a couple of degrees. But no shut down.

    I was worried about the Asus mobo because I've actually read in other forums, before this problem came up, of the voltages not being set to their defaults. right now,

    CPU core: 1.33
    NB core: 1,26
    SB core: 1.54
    DIMM: 1.89

    Are those okay? I will definitely check all my connections again in case a loose wire is causing problems, or if something is caught in the pins.

    I scan for Ad-ware and run CCleaner religiously, but will keep it monitored too.

    As far as BIOS, I originally went to 0602, then flashed back to the previous version (0501). I did that because my computer wouldn't reboot, it would die but never come back up. Someone suggest the new 0602 was to blame. Turns out tho, the true answer (via Asus tech support) was to change the default LDT frequency from 5x to 4x. My computer then started rebooting just fine. Wonder if that now causes random shutdowns?

    Anyway, I'll get to checking the connections soon, after I close shut the jaws of Oblivion some more. Will keep you all updated.
  8. BTW, ...I...I don't have to do anything crazy when it shuts off, I just hit the power button on the case and she comes right up.
  9. did you reseat the processor HeatSink?
    did you use too much Thermal Compound, or non at all?

    :lol: Did you try running the system without VISTA :roll:

    were are you getting the temperature reading from sometimes it is the internal senor inside of the processor and out times it just on the motherboard?

    go a little more in-depth to what happens, does the screen flicker, any weird things on screen, is the system stable on idle.
    does the power supply power down with the system when it turns off.

    did you have a this system on a battery backup... how is your home wiring?

    check behind the motherboard as well.
  10. Quote:

    Then when I decided to try my hand at overclocking, I bumped the CPU voltage back up to 3.5v (stock for my CPU) for stability,

    Eh 3.5 volts is not stock...think you made a big typo.
    I run Optrons with 50% OC's and still keep the voltage at 1.35 volts.
  11. Yeah, I meant 1.35...that's what I get for being in a hurry... :oops:
  12. coldmast: I haven't reset the heatsink, mostly because I used the stock heatsink/fan, and I'm not anxious to try and pull those stupid Intel pins back out of the board. It was scary enough pushing them in the first time. I still have a hard time believing it's a heat problem, because I'm just not seeing significant temp increases from either Everest or PC Probe. Not sure where those sensors are... but I can play Oblivion in 1680x1050 with everything cranked, including 4xAA, for 3 hours straight and have no problems whatsoever (I love you BFG).

    Nothing exciting happens when the comp turns off, just like someone pulls the plug. No flickering, no smells, smoke, warnings, BSOD, nothing.

    It's funny you mention battery backup. I just wrote APC because my PowerChute software is telling me I have 83 minutes of battery power left...not hardly. Plus, a storm blew through Saturday and killed the power to the whole apartment...and my APC battery failed to switch over! I'm going to replace that battery. Could that be causing me power problems, maybe spikes causing my comp to shut down?
  13. Just to wrap this up...the problem was related to my UPS :D got a nice fat 1500VA APC and no more random power losses. Apparently whenever my electricity would flicker the battery backup would kick in, quickly become overloaded, and shut down -- shutting down my computer with it.

    So a nice lesson learned: when you upgrade your power supply, upgrade your UPS too!
  14. Hah, I wouldn't have even thought it was your UPS. Glad you figured that out.
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