I have a hard time believing a rather outdated but formidable PSUs like SS Zeus 750/850w would have trouble powering a GTX 280 card(s), no matter what the IHV opinion regarding this matter. It should never be about the connector, but the real ability of the unit in supplying the amount of power needed by these new beasts of VGA card.
Intel C2D E8400 @4.2 GHz 495x8.5
DFI LanParty LT X38-T2R
DIY Watercooling
Adata Vitesta Extreme PC6400 4 GB kit *2 @DDR2 990 5-5-5-15
HIS HD 4870 512 MB @830-1080
WDC 3200AAKS *2 (RAID 0) + WDC 5000AACS
DVDRW BenQ DW2000 + DVDRW LG GH20NS10
Creative X-Fi XtremeMusic + Creative Inspire T6600 6.1
Silverstone Olympia 750w
TT Kandalf (original)