On the subject, what happens if you have a physX plugged in, but unplug the power jacks from the card? I have a watercooled gtx 260 c216 I plan on using for physX. I know I'll be playing a ton of arma 3, so I'm definitely keeping it for that. But it would be a pain to remove / put it in due to the watercooling. I'd rather just keep it in from the time I set up water on the gtx 480 I just got. Would it be cool to just leave the card there but unplug it from the psu?
I do not think unplugging the two PCIe power connectors from the GTX260 is 'enough'. The system will still detect it and will report with annoying error messages. So, I suggest to take these steps:-
1. In Nvidia Control Panel, choose the GTX480 as the Physx processor
2. In Windows Device Manager, disable the GTX260
I think these steps would put the GTX260 into an idling state and is probably most energy efficient (next to removing the card).