First guess PSU.
GX2's do so love their power.
650W is definately on the wimpy side for my taste.
I run mine on a nice stable voltaged 2kw.
The power consumption of a graphics card is the sum of two powers:
the PCI-Express X16 power: up to 75W
PCI-Express power supply connectors:
up to 75W for the 6-pin version
up to 150W for the 8-pin version
So the max theoretical power consumption of a card can’t exceed 75+75+150 = 300W. So, the 650W are very good to have. Amps are important to, but almost all psu's have enough Amps to power one graphic card.
2000W psu is pure overkill, every bird knows that.
9800 GX2 consume a maximum of 260 Watts. And personally i would never use this old power hungry trash. There a cards that consume much less power and are much faster than this one. Thats my taste.
AND AGAIN khhigdon CLOSE (solve) THIS POST!
This is my last entry here, don't bother to argue, i won't respond.