Not sure if this is the correct forum section to put this in, but I don't know what piece of hardware might be the problem (and thus cannot post in a more specific forum section).
Several weeks ago, my system began showing signs of instability; signs that have not abated no matter what I've tried to do. On occasion during startup, the system will hang after booting into windows, but before windows can load any programs (mouse is unresponsive, and even the keyboard will not toggle the numlock/capslock lights). If the system does not hang during bootup, it has a chance to hang during a game, or when I'm simply browsing the web. First the image will freeze, then a few seconds later the audio is corrupted (endlessly repeating a single fraction-of-a-second of audio), and then the screen goes blank (sometimes black, sometimes grey).
I have tried to pursue this problem on the software side with no luck. I even reformatted and reinstalled windows (Windows 7 64-bit), but this has not solved the problem. This leads me to conclude that it must be a hardware issue, but I don't know enough about hardware problems to trace down which bit of hardware it might be.
Can you list your computer hardware and age of system? If you have other parts laying around you can start swapping them or if you have another computer to move items on that one and see which works and what doesn't. I'd suggest psu and ram to start.
Here's the list of parts and when they were bought:
1x MSI P43-C51 LGA 775 Intel P43 ATX Intel Motherboard
2 x Crucial 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1066 (PC3 8500) Memory - 8 GB total
1 x Antec earthwatts EA500 500W ATX12V Power Supply
1 x Antec P182 ATX Mid Tower Computer Case
1 x VisionTek Radeon HD 4870 512MB 256-bit Video Card
1 x Intel Core 2 Duo E7200 Wolfdale 2.53GHz LGA 775 Dual-Core Processor
1 x Seagate Barracuda 250GB 7200 RPM SATA 3.5" Internal Hard Drive
I've run CHKDSK with no result; I'm currently running Memtest86 (v4.2), and will likely let it run for the rest of the day.
Wouldn't expect it to be the Antec psu. Doesn't sound like a RAM/CPU/GPU/HDD issue. The audio/keyboard/mouse/boot is all motherboard related which isn't easy to test. The only way I know of is to test the rest of the parts and if it's not them then it's the motherboard.
Some additional details: I was never able to successfully hook up the HDD Activity or Computer Power LEDs on the case (the ones that hook into the jumpers on the motherboard). I simply couldn't properly reconcile the diagram in the motherboard manual with the physical jumpers I found inside my case. Though I did hook most of the jumpers correctly (USB, Power Button, Reset Button).
Almost every time the system has hung, I've used the reset button to reboot; but while reinstalling windows the system hung and I attempted to use the normal power button to shut it down: this had no effect, no matter how long I held down the button, it didn't turn off.
Also, sometimes I have to push the power button several times to boot the computer. I don't remember whether that issue developed when I installed the new motherboard or not. I've checked to make sure all the cables are seated properly multiple times, and they are.
Just now, as I was playing Fallout Tactics to kill some time while downloading/installing system updates and drivers and whatnot, I got the hang/audio stutter/screen blank again. This time, however, it was followed by a Blue Screen!
On the screen, the file "atikmpag.sys" was listed as a cause. So now I have something else to go on. Could be the same issue (certainly had the same symptoms) but could be something new, too. Only thing I can think of that's different is that I was able to install Win7 Service Pack 1 on this most recent install (previously I got various errors when trying to do the update, such that I simply stopped trying to install it).