Hey i just bought a gainward 9800gt 1gb green edition card. link here -> http://www.gainward.com/main/vgapro.php?id=212" target="_blank"> Green edition basically means that you do not need to connect an external power supply cable to it. I bought this card because i was worried that my crappy stock psu (400w) would not be able to cope if i hooked up a standard or an overclocked version of this card.
I was wondering if there is much of a performance difference between the two?
As the numbers indicate the card is 8.3% slower. Not a huge deal but you should be able to easily put the card back up to its normal speeds using software such as rivatuner; http://www.guru3d.com/index.php?page=rivatuner
You cannot connect your card to your PSU. It doesn't have a connector to do so. If it does then it should definitely be plugged in.