gmod fix code help for gmod

out of alll the other help and support i have seen it didnt help me at all but i found a code that could help someone and here it is.
-window -dxlevel 81 +mat_forcehardwaresync 0
just go into steam right click on garrys mod then go to properties then set launch options then copy and paste the code. and there you go.

You might want to explain what it does first and the problem it solves, or is supposed to solve. Some people might use this not knowing what exactly it does and have it not solve their problem; plus they probably would not like the reduced graphics and might not know how to change it back.