Did you check the PSU requirements for the 6670 in comparision? Your not going to get much improvement really with the upgrade, simply because of how old a system your running. Your running DDR2 RAM which will bottleneck things, then your hitting the CPU (http://www.techspot.com/review/734-battlefield-4-benchmarks/page6.html) which is another issue though not as bad. I would suggest instead save the cash and look to do a system upgrade complete, since spending the money on a proper PSU PLUS the Video Card would just be a good portion of a new system (like for example get a i5Core $349 Walmart PC, upgrade the PSU to 600W ($99+) and add a Video card you can afford ($149-$500) and get HIGH level graphics at 50FPS in BF4 for example.