By default, Assetto Corsa requires DirectX 10.1 or DirectX 11, and those who attempt to play the game on a DirectX 10 GPU such as NVIDIA GeForce GTS 250 will simply get an error message noting that only GPUs with DX10.1 support are capable of handling the game.

However, the game is playable on DirectX 10 with a simple tweak on one of its files. Here's how.

1.
Go to (Your Steam Directory)/steamapps/common/assettocorsa/system/cfg/ and open graphics.ini using notepad. Be aware that the folder you need to open is not the cfg file you find in the game folder right away.

2.
Change 'ALLOW_UNSUPPORTED_DX10=0' near the bottom of the file to 'ALLOW_UNSUPPORTED_DX10=1'.

3.
Head to Options -> Video -> Effects and uncheck 'Enable post-processing effects'.

There are some things to note, however. As the game doesn't officially support DX10, there will be compromises to make:
1.
Trees and crowds will be rendered with huge untransparent 2D boxes around them as shown in this video.
2. There is no option for features such as motion blur or depth of field.

That's the end of this short guide. I hope this helped those with DX10 graphic cards and good luck!
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