Hello, I'm moderately new to upgrading my pc, and know next to nothing about graphics cards upgrading compatibility. I was wondering if someone could help me figure out what graphics card I can upgrade my computer to (if I can upgrade at all). My intention is to upgrade to play Skyrim at "Ultra" settings (if possible). I'm currently able to put the game to "Ultra" graphics settings, but getting around 20-30 fps and would like to fix up my computer rig to run at least a solid 50+. I am considering upgrading the memory if needs be. Here's what computer I have: Motherboard: Giga-Byte GA-870A-UD3 Processor: AMD Athlon(tm) II X4 640 Processor 3.00 GHz Memory: 4 GB Graphics: NVIDIA GeForce GTS 450 Windows 7 Home Premium (PSU is 700w) Thanks for reading, and all advice in advance!