Originally Posted by BorgOvermind
I'm not 100% sure, but I don't think so. A card expecting 150W from the slot would not run on a 1.0 slot, but the compatibility is 100%. The additional W come from the external connectors.
75W+2x75W from 2x6Pins makes 225. 8-pins are used if power drain is larger then 225W.
A PCI-E with 150W from slot could get to 350+ with the extra 8-pins, which is not the case.
^ you're correct on the wattages.
putting what i said in simpler terms:
drawing more than 75W from the slot wont magically turn the slot off, or anything else like that... if the card has no internal mechanism to deal with the power draw, the wiring feeding the slot will just start to overheat, and bad things can happen.