PSU problem or video card problem?

[SocceRich20]

I have the following system
Silverstone TJ-03
Q6600 (Zalman 9700)
Abit IP35 Pro
4GB G. skill
XFX 8800 Ultra XXX (24" LCD)
XFX 8600GT (Dual 20" LCDs)
Corsair 620 Hx power supply
4x 250 GB SATA (Raid 0)
2x DVD-RW
Vista x64

I have three LCD's, a 24" and
two 20"

I ordered an XFX 8600GT
PCI-e card and added it to
the system. Booted up Fine,
recognized by Vista, showed
option to enable the dual 20"s
on the 8600 GT. I clicked
enable, and the two screens
flashed then displayed faded
scrambled static, then all screens
went blank. Now when I try
to power on the system, I hear a loud constant
beep, despite the fact that I
don't have a case speaker
hooked up to my motherboard.
When I remove the 8600GT
from the system, it boots up
fine once again, but I
need it to work to use all
three of my LCDs. Does
this sound like a power
supply issue or an issue
with the 8600 GT?

 

[SocceRich20]

Update, I tried swapping out the Corsair power supply for a Mushkin 650w, and it booted into windows fine, showed a clear image across all three screens, but then froze. When I restarted the machine, I get the same beeping coming from the motherboard, and no boot. Upon removing the 8600GT once again, system works fine.

 

[SocceRich20]

Update again, put a 7800GTX in the system instead of the 8600, and surprisingly now everything works fine. This rules out a psu problem i would think, as the 8600 runs merely off the PCI-e bus, whereas the 7800GTX requires an additional six pin connector.