| First off, a PhysX card will not improve rendering time, unless the software supports it (which I don't think any do).
Second, a PhysX card was designed to do advanced physic calculations in games, however the games themselves must support it. Few do, so unless you have the games which do support it, you will not benifit much from the card.
Third, DirectX and OpenGL are interfaces for 3D graphics. If your graphics card was designed for compatiblity for OpenGL only, then 3ds Max can only use that. If the card was designed for DirectX only, then thats the one that can be used. Most don't have to worry these days because most cards support both. The test is to try stuff using one, e.g. DirectX, then try OpenGL, and see which one's faster. Then you can use the fastest one. |