EVGA nvidia 9800gtx+ framerate

Hey everyone, hope someone can help me.

Just recently I had my old evga 8800 gts fry on me. Previously, when I played games such as WoW, my framerates were lower than what I presume they should have been at (mostly medium settings, no shadows, etc.), however I was able to maintain around 15 fps in 25 man raids (playable).

Now I have upgraded to the evga 9800 gtx+ and after some minor troubleshooting (drive sweeping and the installing most up to date drivers) was able to get the card stable enough to run the game. When not under any load, frame rates are slightly larger, however even in 10 mans I am taking huge hits in frames, to the point I'm hitting 4-5 fps in 25 mans.

I have tried changing the clock speeds to more or less stock numbers for the gpu, since the card is slightly overclocked to begin with. I've noticed the card runs hot under full load with fan at 100%(100-105 C), but I am currently reworking the cooling in the case to hopefully improve this.

The other concern I have that may lead to this hit in frames is my PSU. The card states it needs a minimum 450w(I have 480w) and 24 amps on the 12V rail (of which I only have 17amps) as well as two 6-pin pci-e power connectors. The power connectors part confuses me slightly, as the contents only included a single 6-pin connector with two plugs to connect to the PSU and there is only one 6-pin connection on the actual card.

Sorry for the long post, but I've been trying to solve this for a few days and I am stumped. In short, could the heat, amps, or something else be creating this problem?

Thanks in advance.

EDIT: I can give further specs, but just wanted to mention my processor is and AMD athlon 64 dual-core 4600+ (2.4 ghz) as I know WoW is also a processor heavy game.