Y'know, the poop might not be so big if you'd put more fiber in your diet! Hey, you said you have big poop around in your life right now.
Anyway, the CX400 is enough:
http://www.guru3d.com/article/msi-geforce-gtx-560-twin-frozer-ii-review/8
Their test system pulled 289W from the wall outlet with one GTX 560 under full load. The CPU was idling during this test, so if I add about 150W to this in order to account for the rest of the system, then that would be 439W. However, the PSU is not 100% efficient, so that means the system would be pulling less than that from the PSU. So if the PSU is 85% efficient, then this means the system would only pull about 370-375W. Except, this would only be possible if both the CPU and GPU were under full load simultaneously.
If you're talking about the 560 Ti, then it's still enough:
http://www.guru3d.com/article/geforce-gtx-560-ti-review/7
319W from the wall plus 150W, factor in 85% efficiency, and it comes out to be 398W if both the CPU and GPU are simultaneously under full load (which of course doesn't really happen).
Plus, I'm adding 150W which is a bit on the high side.