System Reboots Under Heavy Load

Hey everyone, I've used this site as a reference for quite a while and I was unable to find a good answer for this one so here it goes. I just upgraded my PC as follows Case: Coolermaster HAF 932, MoBo: MSI 785GM-E65, PSU: "CU" 700 watts, 12v1 18-12v2-16-12v3-16, CPU: AMD Phenom II X4 945, RAM: Corsair XMS3 4GB (2X4GB) DDR3 1600. Components not mentioned were not upgraded.

So my problem is that when I'm doing something that taxes things pretty heavily (like playing CoD4) the system will reboot without warning. There is no windows error, no nothing. The system won't post when this happens either it just sits there until I remove the power and plug it back in, then it comes up no problem. I'm thinking its probably the PSU I got, it was far cheaper than the comparable Corsair and Thermaltake at Fry's (probably a reason for that). It may also be noteworthy that I have a Logitech G15 backlit keyboard, when the system would reboot unexpetedly like it did the backlight would flicker, kind of like a flourescent light thats going out until I unplugged the system.

When I'm playing other games such as Crysis or Devil May Cry 4 this does not happen (although I haven't played either for extended periods yet). I can also use the system for normal tasks just fine (I'm typing this on it right now). I can't really think of anything else it could be, the PSU was the only thing I really cheaped out on, and if it was a software issue with the game I would think there would be some kind of Windows error message, BSoD, entry in the event long, something, but there isn't. Anyways, thanks in advance for the help. :)

EDIT: Sorry everyone I forgot to mention that I'm pretty positive its not a heating issue, I've got both rivatuner and speedfan running and they are all reporting very acceptable temps, cpu stays around 43C and GPU stays around 68-70C. HDD temps are well below this, 20-35 usually.
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More about system reboots heavy load
  1. Can you link to the PSU you have, "CU 700W" doesnt tell me what brand or model it is. What GPU do you have so we have an idea of the load being put on your PSU.
  2. The box just has "CU" in big letters on it, it has coolmax in the corner so that's probably it, the model number is 700B. The graphics card is an Nvidia GTX260, its worked fine with a 550W PSU for nearly a year now it only started this after I upgraded those above mentioned components.

    EDIT: dang I'm sorry, I don't know how I missed the word link, sleep deprivation probably lol, anyways heres a link to it, lots of crappy reviews to:]
  3. OK, I have an update, I was playing Crysis, everything maxed out, (except AA it was at 4x) and about 5-10 min in it did the exact same thing, seems to point more and more to the PSU...
  4. Best answer
    Replace that PSU. The 12v rails are weak with only pushing 18 amps on the strongest rail. I would expect that to drop under load, which I would assume is causing your reboots as the GPU/CPU eat juice under load.
  5. Concur. Looks like inadequate power.
  6. Could also be a bad memory stick. Sometimes bad memory won't rear it's ugly head until the system is operating under heavy load.
    Just for fun, try removing 1 stick of memory, run for a while, then try with the other stick, see if that makes any difference before you run out and buy that new PSU.
  7. Thx for all the input everyone, I went ahead and replaced the PSU, after reading what you all said and reading the reviews online about this thing (lots of DOA's and failures) I just went out and bought a Corsair 750watt (ofc frys gave me a 70 dollar credit for the garbage psu), far more efficient and has a 60 amp 12v rail, just played crysis for 30 min straight and didn't miss a beat, looks like that did it.
  8. Best answer selected by mrlizard.
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