Narrowing Down a Problem with a New Build - Graphics or Power Supply?

So I've recently put together a new build for myself and have encountered an odd problem. I first encountered the problem when playing games. I would get between 30 seconds - 10 minutes into the game when I would encounter a hard restart of my system. No blue screen, no notification, nothing (Even after disabling Automatic restart int he control panel). This same problem arises with any game I play. I find that lower settings sometimes allow me to play longer before it resets, but it always does. I began to do some testing and came up with the following results:

1. Let Memtest86+ run for ~an hour with zero errros.
2. Ran Prime95 for 30 minutes. All four core temperatures maxed out at 65C +- 3.
3. Tested video card and core temperatures during intensive gaming. Cores max out at the ~65C. Video card maxes out at 75C.
4. Ran MemTestCL. No errors anywhere in video memory.

With the above tests, I felt like the I could eliminate the problem of:
1. Overheating video card or CPU
2. Bad Memory

I then ran one other test that really gives me surprising results. Furmark (the crazy GPU stress test) crashes my system INSTANTLY. I get to look at one frame drawn when the entire system just crashes and restarts. I tried running the test in the lowest resolution, windowed mode possible. In this test, it ran for ~2 seconds before the crash occurred. All very odd considering Battlefield Bad Company 2 runs with graphics maxed at full resolution for 10 minutes at times without crashing.

With this test, I feel like my power supply is the culprit. For some reason my video card just isn't getting the power it needs to run. The test starts, the GPU begins requesting TONS of power, which it doesn't get, so the system crashes. Overheating is definitely not the issue because there's no way my video card could rise from Idle temperatures of 40C to overheating in less than a second, as demonstrated by the Furmark test.

This presents another problem. I really feel like my power supply is completely adequate. My system is:

Intel Core i5-2500 Sandy Bridge 3.3GHz
MSI N560GTX-Ti Hawk GeForce GTX 560 Ti
CORSAIR Vengeance 4GB (1 x 4GB) 240-Pin DDR3 (I had 12 GB but took out 8 during all of this testing)
MSI P67A-GD65 (B3) Motherboard
COOLMAX CL-700B 700W (Note that this power supply is already over a year old, purchased April of last year)

Given all of this info, I come to you all. Is this a power supply issue, despite my PSU being large enough to handle all of this? Perhaps it has gone bad? Could there still be an issue with my video card? Any help at all will get my love.
5 answers Last reply Best Answer
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  1. I couldn't say for sure without looking at the system myself but i would be willing to bet it's the PSU. COOLMAX is considered a cheap brand and some cheap PSU's don't deliver the power they state and can be shoddily built. I would consider replacing it with something like this:
  2. Best answer
    The biggest problem with your PSU is that while the wattage is big enough it comes with 4 12V rails, highest of which is rated for 16A.

    Your card requires 35 A according to the box. So my guess is that the PSU might be the issue, the rails are unable to feed enough amps to the video card.
    If you can borrow a single rail ~600-650W PSU from somewhere it would be easy to test the theory.

    If that does end up being the problem, a good quality Single rail PSU will cost you about $60-90, such as:
    Corsair tx650 v2 $79.99 after rebates.
    XFX Core edition 650W 59.99 after rebates.

    Furmark will really make your video card give everything it can, unlike a gaming setup when there is always some slack. The power draw is also maxed with it.
  3. I too would suspect the PSU. All signs point towards a load-fault. To stoke the fire, Coolmax PSUs are generally over-rated in terms of power output. Coolmax doesn't use RMS (continuous) output wattage ratings like most other manufacturers, but instead lists a PSU's maximum output under ideal conditions. That's the old way of doing things. And since RMS ratings are typically half that of peak/maximum, it then 700W translates into a continuous output of maybe 350W under the same ideal conditions. But the PSUs in our PCs don't always work in ideal conditions.

    Take a look at Hardware Secrets review of a similar Coolmax CUL-750 PSU and you'll see those units simply aren't up to snuff. Two of them blew at about 500W load.

    Having owned an old Coolmax CX-400 myself, I can tell you first-hand it sucked. In a system that didn't use require more than 150W at full load, it barely lasted a full year.
  4. I really appreciate all of the input I've received. It's good to hear that others also think my PSU is the primary issue. It's a shame that Coolmax has kind of a deceptive way to rate their Power supplies, though. I'll be purchasing a new PSU as soon as possible - I'll let you all know if this solves my problem. Thanks!
  5. Best answer selected by andyperfect.
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