Freezing problem when playing games (Please Help)

Hopefully someone can give me their opinions on whats wrong. So I play
alot of graphic intensive computer games, but recently started having
problems. I built a new PC to enjoy these games more and everything
is going fine for a few months, but then I start getting these
periodic freezes. The screen freezes preceded by a chirp, my mouse
turns off, keyboard is not working, but the PC is still running. I
have to manually reboot. So as time goes on these get more and more
frequent. I tried playing different games in case it was a game
related problem, but got the same freeze no matter which game I
tried. I switched out my FX 5900XT for my old Geforce 3 and still got
the freeze. So the way I see it there can really only be 3 culprits:
CPU, Memory, or Motherboard. If anyone has any inkling of what the
problem might be please tell me so I can get it fixed ASAP and RMA
whatever is broke.

Here are my specs

Abit KV8 Pro
Athlon 64 2800+
PQI 512MB DDR400
Geforce FX 5900XT
WD 120GB HDD
XCase 550W PSU

Heat could be a problem- have you checked your CPU and System temps?

Memory would be a likely culprit, and the easiest to check. If your 512MB is
2 DIMMs, remove one. If it still freezes, replace with the other and try
again. If it's a single DIMM, you'll need to find a way to get another to
try.

Check the memory website for operating voltage of the memory. Your board is
probably running it at 2.5V. You may want to bump it up to 2.6V and see if
that makes a difference.

Good luck,

Fitz

i had exactly the same problem recently while playing cs and day of
defeat online , there was a strange little ping and then i just lost
all control and froze for a minute or two, it turned out to be the
little green icon in the bottom right hand corner that tells you when
it is safe to unplug a device was coming on and pinging for no reason
at all, telling me it was safe to unplug hardware when i didnt want
to unplug hardware at all.
It has just stopped doing it recently since i reformatted after
ethernet adapter crashed.
Maybe it was my usb drivers playing up ? ill never really know.

I'll put money on the board about to die, unless there are some O/C's
there not mentioned, they do die, as do all components eventually,
good chance the board has a problem, then heat and so on.

O/S problems ?, run all drive and memory tests, depending on your
brand drive, memtest is an old one but a good one for testing memory,
test PSU voltages.

Remove all extra hardware so there is just enough to run a basic
system and try again.

Does it do it during anything other than games ?

Some small glitches can take forever to find when not physically
there, usually once the basic system is run the problem will show up
easier.

Spyware, Virus, it goes on.