I was just going by the system requirements written on the EVGA box for the card. It says it needs a minimum of 24 amps on the +12v rail.
your PSU has 37a on the 12v rail so you are fine. Like delluser stated your set up on the 12v splits is probably
12v1 - cpu
12v3 - gpu
as is, you won't break 275w at gaming with the GTX550ti