You will see a six port connector on the back edge of the gtx 550ti, make sure you have one of your 12Vdc connectors attached to this port via a 4 pin to 6 pin adapter that should have come with your gtx550ti.
if i dont want to replace my psu but my gpu what are my options
I am thinking of installin gtx 550 ti on my other pc which already cooler master 450 watts(i know cooler master sucks!!! but what can i do
not my fault!!!!!)
I am thinking of buying 6670HD or 7750 HD or any decent gpu for INR 6000(tight budget not flexible)