Need Help! Computer keeps crashing

[PreludeVT]

Ok, my friend got this computer that I builded for him for about 1 1/2 month ago.
It is consists of the following:

Motherboard: MSI KT3 Ultra2
CPU: AMD XP 2000+ (retail version)
Memory: 512 Samsung DDR2700 (1 stick)
Graphic Card: Gainward GeForce4 Ti4200 - 64MB
Sound Card: On-board
Hard Drive: WD 80G SE w/ 8MB cache
DVD-ROM: Lite-On 16x
CD-burner: Some 40X generic brand (don't remember)
Case: Enlight Model# EN-7251 w/ (Enlight brand) 300W PS
OS: Windows 2000 Pro w/ Service Pack 3

So, my problem is that when the computer start and finish loading Win2k (like displaying
the user desktop and stuff), it would just shut off by itself and restart (is like somebody
just unplug the computer from the back). And for a couple of times, I was able to get into
the OS w/o it crashing and I played just one round of the new Need For Speed 2 Demo and
it would crash again. Right after it crashes and reboot and I would go into the BIOS to
check the temperature and it would show 50C+ (so, is this high of a temperature normal??).

Oh, I just installed Win2k on this machine last night, because previously, it got WinXP on it (and
it was doing the same thing, keep restarting). So, I formatted the C drive and just did a clean
install of Win2k.

Thanks.

 

[IgoByte]

Might be the temperature and might be some kind of software...Might also be the PSU...

WHat kind of heatsink & PSU are you using? When did you install Windows 2000?

 

[PreludeVT]

IgoByte,

Since I got the retail version of the XP 2000+ CPU, I am just using the one that
came with the retail version (which I think is sufficient enough, because I am not
overclocking it). Also, I just installed Win2k on this computer last night and it also
crashed during the installation (but it recovered and finished the whole setup process).

It is very strange, because it only crashed once last night and played some games on
it, it was running fine. Then I left it on over night and when I woke up this morning,
I play some more game and it started to reboot and reboot again (right when the
user desktop starts to load up).

 

[lukatmyshu]

I again would second the heatsink problem, make sure that it's seated on properly. The other thing you can do is sit down for an hour or so and start swapping your hardware out. See if running Prime 95 makes it unstable (or if it detects an unstable system) and start changing components until you find out what's wrong.

 

[PreludeVT]

where can I get Prime 95 and what exactly does it do?