The powerful pc's were probably used to brute force through sloppy unoptimized code.
Shouldn't we have seen this at sony demos as well??? According to to what i heard on epicbattleaxes podcast "the AXE Factor" Sony employes have confirmed most if not all Demos on the showfloor were running on PS4 devkits and according to epicbattleaxe the main difference is RAM due to debug tools having to run in the background.
They also brought up the excellent point of deception that went on at the demo booths.
It clearly stated XBOX ONE in bright glowing letters above the demo booth and the people were handed the Xbone Controllers.
When in reality people were playing on High end PCs running windows 7 (Xbone OS is supposed to be windows 8 based) where the graphics card alone costs about as much as the whole system they are supposed to represent.