Nah wasn't suggesting that, was just pointing out that I think its down to current draw in general rather than amount of usb devices plugged in.

Even so 4.2ghz isnt a big overclock tbh. I hit this issue over about 4.5 and get it 50/50 on boot at 4.7 or higher. Its worse if its a reset after a stability test freeze. Im almost guaranteed to have no usb until I reset again.