Even if it was a GTX 580, I'd expect the system to turn on...In case you didn't pick it up, the majority of the power draw in most systems is from the graphics card (if using a higher-end one for gaming) and then the CPU. Motherboard, hard drive, RAM, peripherals, fans, etc. have fairly low power consumption in general. Hard drives use a couple dozen watts on spin up, but not after they've already started. That's generally not an issue unless you have many many hard drives.
Check all the connections. Do the paper clip test, bridging green/black wires on the motherboard 24-pin connector to jump the PSU and see if it turns on, etc.
It's either the power supply is DOA and you should return it, or there was an improper installation.
Edited by mikeaj - 7/30/11 at 8:44pm