Wiring my pc

Im running a corsair 650tx powering an e8400 2 hard drives some case fans etc and a oc 9800gtx. i was thinking about dropping in my old 8600 gts as a dedicated physics card but i dont know if my psu can handle the load. Also having only 1 8 pin connector i cant seem to figure out how im going to wire it even if it can take it. I didnt wire it myself but it looks like he spliced my spare 4 pins to power my fans. I want to make sure my psu can actually take the load before i tear professional wireing apart. :)

I can't give you a "yes" or "no" reply myself, but you should keep in mind that the power supply's overall wattage should exceed (by a 10 or 15% mark) the overall requirement of your rig. So if you'll be requiring a total of 500W (as a random example), get a 550W psu. Never let your components perform at near 100% since that's generally not gonna help you much (thus why manufacturers lower the frequency from the maximum of the components they sell, and oclocking generally voids the warranty).

Ya ill do more research. Been honestly trying to find some kind of wiring diagram or guide as well. I dont know **** about electical work and am terrified ill blow the damn thing up lol.