sup guys, so a friend gave me this PC for my birthday, absolute horseshit, cereal can get me more FPS in tetris than that blender did, but well i decided to upgrade it without hurting my pocket, so i bought:
1x Core i3 540 @3.4 Ghz
1x DDR3 Corsair 4 GB 1333 Mhz
1x SATA II 1TB HDD
1x Corsair 500 watt PSU
1x Lightscribe DVD-RW Dual Layer
1x PCI WI-FI adapter

so i was doing well with my Intel GMA 3000 but performance was extremely poor, so i have decided to buy a Sapphire Radeon HD 6950 2GB Priced @260-300
but i started reading reviews and apparently this uses 2 PCI-E power connectors, and i got concerned about my PSU so i want to know, do i HAVE (like no other way) to buy a Power Supply?
PD: a friend gave me his old GeForce 210 and i havent got any unxpected Reboots or something like that indicating lack of power.
help me out please! dont want to sped 100 more on a 750 watt PSU....
EDIT: just for you to know my MOBO is CrossfireX capable. and dont get me wrong i just dont like Nvidia..