Not powering a graphics card?

Depends on the GPU, sometimes it will cause the system not to boot because it throws a POST error due to lack of power, other times the system will work just fine without it, it wont damage the GPU, the GPU just wont function properly.

Thanks.

What I was referring to is for example if I had my GTX 470 SC in my primary slot and it had full power and I just decided to throw in a lets say 9800GTX way at the bottom but decided not to power it because I wasn't using it, I would have it plugged in but without any juice. If the system would boot up fine, would I want to worry about leaving it in there?

That raises the question, why are you leaving it unplugged? It will still be pulling 75W of power through the board, it wont pull too much from a PCI-e cable so you wouldnt gain much by leaving it unplugged.

I'm not leaving it unplugged, just curious =D

It shouldnt damage it or do anything bad, when undervolted or underpowered electronics just tend not to work, its when you start over volting it that you can run into issues.

Yeah I figured as much, I was just wondering how a card that was not being used as a primary display adapter and not being powered would react.

Thanks for the insight.

Well, it is still being powered, a 9800GTX can get the vast majority of the power it needs to fun at full load without the PCI-E cable, it just needs that extra little bit to be able to handle running at full speed.