Really dislike your power supply. That is the one area of a build I am uncompromising. Stick with seasonic, antec, corsair, xfx, pcpc, flower... Thats the one thing that can really mess up your system.
I also prefer air cooler than the intel liquid cooling option, but thats a personal preference...
In the future I would suggest posting the question on these forums BEFORE you order the parts.
The triple channel RAM will "work", just you will not get optimum performance out of it. X79 platform is designed for 4-channel RAM (with 4 sticks). If you buy another RAM stick of the same specifications as the triple channel kit you bought, that should work fine ... its always best to buy it in 4-channel (or 2channel for Sandy Bridge 1155) as the manufacturers can guarantee compatibility!
I'm just going off the price, and the fact that I've have't heard of that PSU brand before. $40 for 700W seems too good to be true ... and it probably is! Corsair/Seasonic is always the safest option with PSUs!
AMD and Adobe are currently working on GPU acceleration for all their apps (especially for the APUs) so if GPU support isn't already available with Photoshop/etc it soon will be!
See if you can make changes if possible, if not ... everything will work if you plug it in ... just not necessarily the best value/performance!
AMD's 7900 cards are far faster than any Nvidia card for computer performance except for some Quadros and Teslas and even then... 7900 is dame fast and beats some Quadro/Tesla cards that are several times more expensive. Photoshop is already compatible with AMD cards through Direct Compute or OpenCL.