I don't use the 2D but I see you have an X79 motherboard. Make sure you have the latest drivers as earlier drivers could not run surround on the X79 boards and caused me major problems with black screens and crashing. I also had to make sure that I didn't overclock the memory which seemed to cause problems with my gtx 590.
Rod Sayers
This is my fsx.cfg.
I am using three dell monitors and have no real stretching. The bevel resolution is higher than the recommended setting and seems to work best for my screens. With lower resolutions or wideview aspect I do get distortion. The only issue is that at this resolution it is difficult to back the view far enough to see the entire cockpit at once. However the 737 NGX is awesome.
[DISPLAY.Device.NVIDIA GeForce GTX 590.0]
AntiAlias=1
Mode=8169x1440x32
TriLinear=1
Rod sayers
Apologies I mean't wide view aspect.
When I had this problem with my three screen set up I solved the problem by setting wideview aspect to false and then making sure that FSX was at the same resolution as my bevel corrected resolution in the nvidia control panel.
It removed all stretching for me.
Worth checking in your fsx.cfg that it has picked up your cards and resolution. I had to delete the fsx.cfg and let it be rebuilt by FSX because it hadn't recognised the upgrade to a gtx 590.
Rod Sayers