Try switching your PhysX Engine to 3.x, seeing as you have the PhysX 3.4 DCC plugin installed. You don’t need to restart to enable this.
In my PhysX simulation with rigid bodies and using 3.x, GPU usage hovers around 5-8% during the sim, and effectively tripling the speed. The simulation time is reduced considerably, to about 33%. I can’t find a way to time the simulation accurately (outside of manually with an app), but sim times were:
All sims are 452 frames, Visualization turned off. Enabling visualization will max your GPU.
PhysX 2.x (2.8.5), with Multithreaded and Hardware Acceleration: 4m 38s
PhysX 2.x (2.8.5), with multithread, no hardware accel: 4m 26s,
PhysX 2.x (2.8.5), no multithread, no hardware accel: 4m 26s
All test showed GPU in 3dsmax.exe running 5-8% and CPU pinned at ~12.5% (one of 8 cores).
Some rigid bodies never moved in the whole sim.
PhysX 3.x (3.3.4), with multithreaded and Hardware Acceleration 1m 36s,
PhysX 3.x (3.3.4), with multithreaded and no Hardware Acceleration 1m 36s,
PhysX 3.x (3.3.4), no multithread, no hardware accel: 1m 37s,
All test showed GPU in 3dsmax.exe running 5-8% and CPU pinned at ~12.5% (one of 8 cores)
All rigid bodies simulated properly.
The variance in these shows me that these checkboxes mean more or less nothing, and probably caused by human error and scene setup time. However PhysX 3.x is definitely the way to go, for both speed and scene completeness.
The GPU utilization may vary greatly depending if you’re using soft bodies/cloth systems etc.