Do Corsair PSUs have the appropriate connectors for the 9800GX2?
There is a mechanical issue with the 9800 cards and virtually ALL PSUs. Nvidia has made the locking tab slot on the card narrow enough that most 8pin and most 6+2 pin connectors will not fully snap in. They will work electrically but, the tab will not lock the connector into the slot on the card.
Corsair PSU's will work just fine electrically but you may either have to leave the tab out of the slot temporarily or cut the tab off. Nvidia is supposed to supply their partners with a proper adapter within a couple of weeks to negate the need for this. If you can't wait or if your cable will not work with the tab on it, you can clip the tab off the PCI-e cable.
OFFICIAL CORSAIR STATEMENT: If you need to clip the tab on the PCI-e connector to make the connector work with these cards, it DOES NOT constitute a voided warranty.
Any other modifications to the cables or PSU as stated by the warranty terms WILL constitute a voided warranty.