I don't know what's your problem about, but with a GTX 780 and an i5-3570K you should be able to play GTA: IV and its episodes perfectly. That game is bad optimized for PC, however.
I don't know what's your problem about, but with a GTX 780 and an i5-3570K you should be able to play GTA: IV and its episodes perfectly. That game is bad optimized for PC, however.