It currently has a AMD A4-3400 Llano 2.7GHz, but I want to upgrade it to an A8 and am wondering which one would work best. I currently have 8GB of DDR3, Windows 64 Premium Home and it has the AMD Radeon HD 6410D Graphics built in, with a 500W psu. I want to get a new graphic card, but am not sure what will work best.