I'll add that I just installed a 2G GTX 750 Ti SC by EVGA and it works great. You'll need to remove the AMDdrivers first, and be sure to get the SC version of the card ( a short version). I also got a GT 740 1G to run fine.
Some 8300s came with a 350 watt PS, but the 460 watt PS has two 6-pin...