PCIe bus speed x16

Okay I been asking this question at Asus's fourm but it seems nobody can help me there. Actully I am not even sure if this is a real problem.

First let me tell you want system I have:

Asus P6T (standard not deluxe!)
Intel i7-920 (currently not OC)
6GB OCZ 1600 DDR3 Tri-channel
Corsair H50 Cooler
Seagate 1TB HDD
2 PNY GTS-250 SLI
Corsair TX650

Okay well I had a previous problem with my video card's and getting the BSOD but that is now fixed. But now the problem that PNY has told me about is that when I submitted the nvidia system information to them through email they said they didn't understand why one of the PCIe slots was running at x16 which is normal and the other was only running at x8 which they said it should be running at x16.

I have updated the bios and even updated the video drivers even took both cards out and used one at a time in both slots and get x16 but when both are in they arn in one runs at x8. I looked through the bios and there is no way to change the north bridge settings. So my real question is is this normal or do I have a problem?