M05K :
Will buy an XFX 750w, btw, the CPU will be good for the new games for sometime? Or i'll need to change it? I will not get the full perfomance because the PCI-E version?
which XFX PSU are you looking at? (If you've got a link post it
)
PCI-E version shouldn't matter, modern GPUs (including the r9 280) don't saturate PCI-E 2.0 x8 slots as of yet (except for maybe the r9 295x2 or Titan Z) so PCI-E 2.0 x16 should be golden
As for the CPU, you should be fine for now, but you will may need to upgrade it in 12-18 months time, however this time scale is just a rough guess