Problems running games on new system, please help!

I recently built my first system, and it runs terrifically in everything except games. Nearly every game I've run on it has had problems, and since the same problems have occured in multiple games, I think the problems may be hardware related, so I'm posting here in a desperate plea for help.

First off, here's the system specs:

Opteron 165 (not OC'd as of yet)
DFI nF4 Ultra-D
2GB OCZ Gold PC4000
eVGA 7800GT
WD Raptor 150GB

All drivers are completely up to date, as is DirectX, Windows XP (Pro SP2), and each game has been given the most recent patches. There are two main problems I have had.

1. The game will "freeze" for about 1-15 secs, not changing any display and not accepting any type of user commands. Sound continues (in F.E.A.R. the sound continues almost uninterrupted, in Half Life 2 the sound repeates a short segment (about a second) over and over). Afterwards, user control is completely restored. The frequency of this varies, but it happens at least every few minutes. In F.E.A.R. it has completely crashed my system (blue screen) twice. I am fairly certain this isn't due to any kind of hardware limitation, since it happens in Half Life: Source 1 too (a much more outdated game graphics wise).

2. Another more minor problem that I have observed in F.E.A.R., Half Life 2, and Age of Empires III is almost certainly graphics related. Certain areas of the rendering will "flicker" with a stark white polygone that seems to conform to one of the renderred surfaces. That's the best way I can describe it really...

Any thoughts on either of these problems would be most appreciated. If any more details would help, please don't hesitate to ask. Thanks!

The power supply I'm running is an Antec TruePower 2.0 550W so in theory that shouldn't be a problem, though of course it's possible it's just a bad unit (though there is no evidence of this other than game performance). Is it possible I could have made an error in connecting it or something?

As for the mobo, this one has two PCI-E x16 slots. Should I perhaps try switching my graphics card to the other one as a troublishooting option?

Besides these ideas, are there any other thoughs on how I can isolate the problem short of actually replacing these or other hardware components?

Thanks!

yeah you should btw dfi its that the top slot operates at 16x but the bottom slot operates at 1x unless in sli but in asus you could change the slot speed by putting a graphics card

lol dvdpiddy

Alright, thanks. I just appreciated what you had to say, and wanted to make sure I was able to give you the further info. Thanks for the tip though. :-P

First off please backup any important data you have on your system!

You might want to try downloading:

http://www.kernel.org/pub/dist/kno [...] -23-EN.iso

Burn the ISO to CD with http://isorecorder.alexfeinman.com/isorecorder.htm

Boot from it and see what kind of performance you get.

Type in: memtest <enter> @ the boot prompt let it run memtest for about 2 - 12 hours

If it passes the memtest which it should boot into Knoppix get a command prompt and run

[knoppix@knoppix ~] $ su -

[root@knoppix ~] # cat /dev/sda > /dev/null

See if you get any I/O errors

Good Luck