please help my new computer. it's sick

[warrantofice]

I just bought a new computer and decided, hell, i made one 8 years ago, why don't i get some beers and slap together a new one...well this don't always turn out as they should.(i do actually know a bit about computers and i would really appreciate some help)

The setup:
case - No name case w/ 450w powersupply
motherboard - Asus M2A-VM (atx micro with onboard video)
video card - Sapphire x1950 ATI
ram - OCZ 2gb
monitor - Dell 24"

The Problem: My computer just freezes on me. Completely locks up. So bad that I have to use the manuel I/O power reset on the back of the case. It seems to mostly do this while displaying graphics but has done it at other times aswell. Installed CS-Source and the computer would lock up completely after about 2 minutes of play. Under regular desktop use i get about 30 minutes of play. (mouse freezes/keyboard doesn't work/screen goes black or just freezes in place)

What i've done:
-drivers update for - asus bios / graphics cards / motherboard / monitor update / updated windows

Please help!
If you have any idea it would really be helpful or any suggestions on how to isolate the problem so that i can narrow the problem down.

thanks warrant

[warrantofice]

I'm thinking it could be the power supply or the motherboard but i don't know how to diagnose either problem

[RedRover]

sounds like a cooling issue since it crashes faster when you put a lot of stress on the processor (HL). you dont mention what CPU you're using or what you're doing for fan/heatsink

[warrantofice]

I have an AMD 4400+ processor and using the stock cooling that was supplied with it.

I only have single case fan.

my ati catalyst program says the video card is running at 40c which i don't know if it is good or bad, but doesn't seem horrible.

[SamIAm]

Run same stress tests on both the CPU and the memory, and see what breaks first.

[warrantofice]

what program do i use to run those? and how will it record it if it just complete freezes up? does it write to the hd while its doing it?