Custom FSX computer spec help please?

Hi, so I'm a flight simulator enthusiast and this is what I want out of the game;

To run on 3 screens,
have at least 20-25fps ,
be able to install add-ons that will run seamlessly,
be able to max out the graphics.

So I have been looking at computer components and for the new computer this is what I am thinking;

-CPU - Intel Core i7-2600K (3.4GHz, 8MB Cache)
-Motherboard - Asus P8Z77-V LX: USB 3.0 SAATA 6GBs, ATI CrossfireX
-RAM - 16GB KINGSTON HYPER-X GENESIS DUAL-DDR3 1600MHz
-GPU - 2x 1GB AMD RADEON HD6790
- Hard Drive - 500GB 3.5" SATA-3 6GB/s
-Power supply - CORSAIR 650W Enthusiast Series TX650 V2-80
-CPU cooling - Standard intel cooler

Including all standard sound cards and network facilities, Will all of this be compatible? and will it run the game how I want it?

Thanks for the help guys much appreciated!

Ps. Been researching more and ive found that maybe 2 NVIDIA cards would be better in SLI mode as the clouds for the AMD cards dont work in fsx what you think and which cards?