New computer very unstable

[carnetarian]

My new computer has been having a couple problems:

#1:
I'll be playing Crysis, and a bunch of random pixels will appear at the top of the screen and whatever sound is currently playing will start repeating itself over and over again. Then the screen goes solid black until I restart the computer.

#2:
I'll be browsing the internet, or doing something else that's low key, and then the monitor will go black with no warning at all. All the computer fans will still be running, and I'll still hear the hard drive spinning, but the screen will stay black until I hit the reset button. I know this isn't a problem with the monitor, because I use the same one with my laptop and it never has any problems.

#3:
Screen turns black with random blocks of colors, then goes back to normal. A message box comes up saying device driver has failed, but recovered.

Between these problems I'm lucky to go two hours without having the computer crash on me.

I've tried updating all the drivers, patching Crysis, and running Memtest86+ (which I ran for 2 passes with no errors), but that is where my experience with troubleshooting computers ends. This is the first computer I've built so I don't have any spare parts to swap in. If anyone can help me diagnose/fix the problem I will greatly appreciate it.

Here is my build:
os: vista home premium 64
cpu: intel e8400
gpu: ati 4850
mobo: asus p5q pro
ram: patriot extreme performance 4gb ddr2800
hdd: Western Digital Caviar SE16 WD6400AAKS 640GB 7200 RPM SATA
psu: PC Power & Cooling 610W Silencer

 

[harrycat88]

It sounds like a cooling problem on your video card. You might want to check that the fan on the 4850 is spinning and make sure the fan/heatsink is firmly attached to the video card. If the fan is spinning but the card is extremely hot, you might want to download ATI Tool or RivaTuner to set the fan speed to max manually.

I purchased a 3850 AGP from Newegg a couple weeks ago that came with a DOA fan that I had to replace.

 

[killyou400p]

Temperature problems?
Cooling specs?
I had the same problem playing on my overlocked 8600gt and had random pixels flickering till it turns all black, then have to start the computer over. Sometimes even the BSOD came out. I corrected my temperatures and it stopped. Also put down a little overclocking.

 

[carnetarian]

I checked the fan on the gpu and it's running. Right now the gpu temp is 77C and I haven't been doing anything with my computer except browsing the internet (I don't know if that's bad or not though). I'm not overclocking the computer at all, and I'm using the stock cooling systems for both the gpu and cpu. The cpu temp right now is 43C according to PC Probe and 58C according to core temp (I have no idea which one is right). I'm going to try downloading ATI tool and see if that helps at all.