Determining full load for CPU/GPU/Motherboard

Hey guys, I've searched everywhere and have seen many differing opinions on what PSU I need. I'm currently confused about if I would actually ever get the GPU, CPU, MB, etc on full load IRL.

I'm trying to build a PC around these, for Battlefield 3 (my old build for CS:S won't do anymore ):
-Case with 5 140mm fans ~idk
-NZXT Sentry-2 ~idk
-Intel i5 2500k ~150w full load
-Scythe Mugen (120mm fan) ~idk
-MSI P67 GD-55 MB ~120w, 150w with pci-e used, so im guessing 180w with SLI?
-G.Skill 8gb ddr3 at 1600 ~3w
-Gigabyte GTX 560 Ti SOC x2 ~400w (200w x 2)
-1 SSD, 2 500gb WD Black HDDs ~20w total i think

If I did that right, then I would need 753w plus power for the case fans and fan controller. That doesn't seem right to me though. Would I ever reach a point where everything is on full load? Especially the GPUs and CPU? I was thinking I might be able to get away with a 600w supply (from my old case). And if I need a 750w+ PSU, anyone have any recommendations around the $100 price point?

IRL, I would use the build solely for BF3, a lot of heavy RAW photo editing and some HD editing.

Thanks in advance and sorry to the TLDR-ers if I write a lot.

You could probably run it on a 550W.

A 600W system would run a single 580. 750W could easily run dual anything except a 580/6990/590.

Thanks!