I don’t understand your comment and I may have misunderstood what you were originally trying to say as well. It seemed as if you were confusing an APU with and AGP graphics card. If not, just ignore what I said.
As for frying a card by not plugging in the power cables, I can’t say definitively, but I know I’ve done that a few times myself with no problems. In fact I built several machines last year that needed high end Radeon HD79xx and HD78xx GPU’s and I regularly would forget to plug in the power cables. However I did tend to only buy one particular brand of card - Powercolor, which I’ve found to be the most reliable. But they also tend to cost more. So this may not be true for all brands.