I can’t find the « Preview DirectX 10 » box in the settings of FSX. What should I do ?

First, check that you have FSX-SP2 installed on your computer. Indeed, the « Preview DirectX 10 » only appears if you have installed the SP2 patch or if you have FSX Acceleration or FSX Gold or FSX Steam Edition.

Below you can download both patches

Download the SP1

Download the SP2