Computer trouble

Ok i bought a new pc recently. Evga Mobo, amd sli version. And an Evga
geforce 6800 xt 256. I get the dreaded nv4_disp.dll error a lot for 2
weeks. so i send back the video card and get a replacement. I put it in
last night, start up World of Warcraft and it give me the error again.
I restart the computer in agony and decide to go into the bios for the
100th time. I see a setting for pci-express bandwidth Tlp and its set
at 4000 something bytes. I decide to try something new so i turn it
down to 512. I save and start the pc up. I load up WoW and it works.
For over 2 hours until i turned it off. It used to give me the error at
around 15-20 mins, sometimes less.
Does anyone know if turning the tlp down could have some bad side
effects? Im not even sure this fixed my problem because Elder Scrolls
oblivion still freezes on me. But does anyone know of anything else
that might help keep this problem away for good?