I'm using 2 GTX 780TI SLI card and the FPS reach 35% more on my 4K monitor vs my old Full Hd one (but 120 hz)
What i did with my old x58 - I920 (Overclock to 4gz after installation) - 2 SSD intel SATA II - Soundblaster Reco 3D - 1000w Quiet
1) Plug your cards but Uninstall your graphic drivers first with safe mode or by choosing vga standard card. Option: use registry cleaner to delete all Nvidia entries
2) Choose the physicX option to GPU (not automatic, never) after lastest Nvidia drivers installation as Administrator
3) Don't overclock your CPU during those phases
4) Clean all Prepar3d V2 profile file after backuping it
5) Let the Prepar3d choosing the default option
6) Follow this tips http://www.nvidia.in/object/slizone-appprofile-in.html
7) Recalculate the Mask and let 3 virtuals processor core free
8) Start the Prepar3d V2.4 once and check the fps
9) Restore the config line (Addons) one by one and check which one is lack of preformance with SLI
On my conf, the only heavy trouble i had was related to:
- Ultimate Traffic 2
- Rex Essential
- FSX scenery like Roissy LFPG, EGLL and so KLAX, KJFK high definition because is not fully Directx compatible or the CPU is too low !
Hope it will help
Fervex
PS: Sorry for my english, i'm french. Nobody's perfect.