Asus P5N-D pci-e failure?

Hi there everyone, okay im going to put this very simple because im very tired (I'm from Sweden and its about 9pm here and I've had a long frustrating day!).

I bought these items to upgrade my PC since it was about 5 years old at the time.

Asus P5N-D 750i SLI
Geforce 9800GT
Corsair 450watt

--------------------------
rest of the old setup
Corsair 2gb 800mhz 4-4-4-12
prescott 3.4ghz (yea I know..money folks..money!)
500gig seagate

So, whats my problem then?
Well the graphic card wont give me a picture, and I've tried the card in two different PCs, and it worked without a problem in both of these PCs.
So its not the card failuring, its all leaning towards the motherboard, but the things is my old graphics card is working fine,
its a ATI X850XT so it doesnt need 2.0 pci-e.

I'm wondering if there are any programs to check my motherboard for errors or so?
I've found Memtest, but I havent got access to a cdburner right now, I might be able to soon though.

Like I mentioned im very tired so it wouldnt surprise me if there are parts that are unclear so please ask and ill try and explain it better.

Regards, Seb.

I did, and the other 2 pcs have alot older Psus then mine so thats not the problem

Have you updated to the lastest BIOS? Try that first if you haven't yet.