I have a fairly high end gaming computer. My FSX SE Settings are not maxed out. While in flight I noticed the buildings are little black boxes. I suspect it's my Nvidia Settings or maybe one setting that needs to be changed.

Any ideas on which setting needs to be looked at first?

Have you tried HIGHMEM FIX?

Reach out to AVSIM Admin Jim Young, he can best guide you

I believe FSX SE already has that incorporated.