EAH 4870 Random crashing

Greets everyone i'm having a problem with my system. Randomly when i'm playing games like COD-2 the screen will turn black and seconds later the computer will restart. I'm in Windows 7 64 bit edition, here are my system specs.


(Info takin from GPU-Z)
EAH dark knight 4870
-GPU RV770
-Shaders 800 unified
-pixel fillrate 12.0 Gpixel/s
-memory type GDDR5
-Memory Size 1024
-GPU clock 750 mhz
-Default Clock 750
-Memory 900Mhz both

(info From CPUID)
AMD Phenom II X4 940 processor 3.0ghz
- Socket AM2+ (940
- Core Voltage 1.328v
- Core Speed-3000.0 MHz
- Multiplier x15
- Bus Speed 200.0 MHz
- HT Link- 1800

Motherboard
-M4N72-E
Chipset Nvidia

Memory
- Type DDR2
- Size 4096 MB
- Channels #- Dual
- NB Frequency 1800.0 MHz
- Dram Frequency 400 MHz

Power supply is 600 watt

If you need more info don't hesitate to ask

The first thing I'd do is return everything to default clocks and voltages. If you've overclocked anything, reverting it back to stock is a good general troubleshooting step.

Next, uninstall and reinstall the video drivers. From ATI's website:

After this, download and reinstall the latest drivers.

If you still have problems, your system may be overheating. There are many temperature monitoring programs, but CPUID has an easy to use and free program in HWMonitor http://www.cpuid.com/hwmonitor.php This will allow you to monitor both the processor and video card temps. The CPU getting to hot would likely cause a random restart.

That's probably your answer, then. Power supplies often do not go quickly or quietly. Random restarts is a common sign of a power supply that is beginning to fail.

I myself had a computer about 3 years ago that started to reset randomly. As my power supply wasn't the most reputable brand, I was fortunate enough to suspect it first. The problem cleared up after replacing the bad PSU.

If you're able, borrowing or using a spare power supply (PSU) would be the best bet, as you don't need to make any investment to make sure this is the cause of your issue. Unfortunately while a power supply can be tested, as you've seen your PSU still gives good power most of the time, it just wavers occasionally enough to where it can't provide the current required by your games.

Out of curiosity, can you provide the brand and model of the power supply?

If you can give the brand and model name/number, or failing that, put up a picture of the PSU's specifications sticker, that would help. It sounds distinctly like a power issue.

Have you experienced the issue only in heavy 3D environments likes games and benchmarks? Complete shutdown/restarts are often the product of power supply problems, especially considering what you have already done to try diagnose the issue.

Any ideas other then a power supply issue?