Ok so I just did one big purchase right: Intel i7-2600K
XFX Radeon HD 6970
AsRock Fatal1ty P67 Professional B3
16GB DDR-3 1600 RipjawX
OCZ 60GB Vertex3 SSD
iiyama ProLite E2473HDS-B1
Silent Pro Gold 800W
LG Blu-ray burner
GXT 18 Gaming Keyboard
Seeing as USB is 500ma @ 5v, the maximum load would be 2.5w... which is nothing at all (so even if the G19 took all it's power from USB - it's still inconsequential)