PCI Express v1.0 or v1.1 Motherboard???

I recently started having graphic card issues with my "XFX PVT71UZDF9 Geforce 7950x2 1GB 512-bit (256-bitx2) GDDR3 PCI Express x16 HDCP Ready SLI Supported Xtreme HDCP video card" on my "ASUS A8N-SLI 939 NVIDIA nForce4 SLI ATX AMD motherboard" I reverted back to my old RADEON 9250 for now. After finding out that my graphic card wasn't under warranty I figured it would just be more cost effective to just get a new one since its over 2.5 years old. After some research I found some good graphic cards that are PCI Express 2.0, not sure what the difference was so I wiki PCI-E 2.0 to learn more. I know that 2.0 graphic cards are backwards compatible up to 1.1, however I don't know if my motherboard is PCI-E v1.0 or v1.1. I tried checking the specs of my motherboard but it doesn't say anything dealing with version. Is there some way for me to find out? o_O