Please follow this thread here:
http://www.fsdreamteam.com/forum/index.php/topic,18029.0.htmlIt's possible that using such old version of FSX, especially with a new video card, which is not really optimized/ for DX9, might expose some bugs in the ancient FSX rendering engine, which nobody would fix.
FSX SP2 is probably the worse version to use, since it has additional bugs which were not present in the Acceleration Pack.
If you *really* must use FSX, it's best you would at least use the latest version of it, which is FSX:Steam Edition. However, the real solution would be switching to Prepar3D4, which is 64 bit and used DX11, so it will make better use of modern hardware.
We won't do any scenery for FSX, starting with the next one (KORD V2), and several other famous scenery developers are doing the same, see here:
http://www.fsdreamteam.com/forum/index.php/topic,16116.0.html