So I have this gateway dx4380g-uw308 desktop. I bought it because of my limited budget and it has worked well for games up to this point. However, I recently decided that I wanted a little bit more and ordered some new hardware. I ordered a new GPU - hd 7770 and a new PSU to feed it. With everything else stock, is this setup going to be efficient for running games at decent frame rates? This system came with an a6-5400k APU and I don't have the money for another cpu at this point. I'm assuming that the dedicated hd 7770 card will override the built in graphics and the apu will in turn operate as a cpu, solely? Also, is this a relatively straight forward upgrade, install and start? Or what else will be necessary? I'm primarily confused by the relationship between the apu and gpu. Thanks, John.