Microsoft originally promised full DX10 support for FSX, leveraging the new Vista operating system. However, due to internal pressures and a shifting development cycle, they shipped FSX with a "Preview" mode. This mode allowed the rendering engine to switch from DX9 to DX10, theoretically shifting more work from the CPU to the GPU.
The impact of tools like "Steve's DX10 Fixer" can be significant for: steve%27s dx10 fixer
The Fixer introduces a configurable water shader that rivals early Prepar3D visuals. You can adjust wave height, specularity, and reflection mapping. It also fixes the infamous "runway lights floating above the tarmac" by re-anchoring light sprites to the ground polygon. Microsoft originally promised full DX10 support for FSX,