your PSU does not have enough amps for the 8800GTS 512 or 9800GTX+
you can run a 9800GT or 9600GT on it. I have run both on that exact same power supply. Just use the adapter that comes with the cards for the attached power cable.
Can you help me out here , i have the 9800 GT from BFG , the Eco-Intelligence edition and it uses 30% less power than the regular ones. I see that you have the regular one running on a 300 watt PSU. So how is it running so far , does your computer crash when playing demanding games .... ?
Do you think I'll be able to run mine on my 300W PSU. So far everything on my PC runs perfect , games are stable and there are no crashes , what do you think ?