as a former gtx 460 holder i can asure you that you will be fine. I did run it on a 500 W PSU with 32 Amps on the 12V rail (i had the gtx 460 1GB/256bit 675 Mhz stock and OCd it to 775Mhz)
It should be fine, but when you ask about PSUs and power you should list all components for a good answer. If you have a lot of other components and a power hungry CPU the 550 W might not be sufficient. In most cases yes.
as a former gtx 460 holder i can asure you that you will be fine. I did run it on a 500 W PSU with 32 Amps on the 12V rail (i had the gtx 460 1GB/256bit 675 Mhz stock and OCd it to 775Mhz)