NVIDIA Forceware 257 & Heterogeneous GPU PhysX: It's a Bug, Not a Feature

Our inbox quickly lit up this morning when we received notice about this NGOHQ article, discussing how NVIDIA had removed the heterogeneous GPU restriction on PhysX in their latest beta drivers.
This struck us as a bit of an odd reversal of positions from NVIDIA, and now that we've had a chance to chat with them we finally know what's going on.

As a quick matter of background, starting with the Forceware 186 series NVIDIA blocked GPU/PPU-accelerated PhysX from working on NVIDIA GPUs and AGEIA PPUs whenever a non-NVIDIA GPU was detected as being in the system. It's been a polarizing matter for the GPU community for nearly a year now, with a tug-of-war going on between projects editing the drivers to remove the block, and NVIDIA adding further checks in to their drivers to stop those efforts. In any case, there has been no sign that NVIDIA would be changing their position any time soon.

This brings us to this week's Forceware 257.15 beta drivers and today's clarification from NVIDIA. NGOHQ was correct in that the 257.15 drivers lacked the heterogeneous GPU restriction; however there has been a question of intentions. As we stated previously NVIDIA has held steady to their desire to keep PhysX on pure NVIDIA systems, so to make this change without publically announcing it odd - if only because it deprives them of the chance to sell cards as PhysX accelerators.

We just got done talking with NVIDIA about the matter and they clarified the issue for us. In what we expect is going to be a disappointment for many of you, the lack of a PhysX restriction on the current 257.15 beta drivers is a bug, not a feature - the restriction should have been in those drivers and it was not. NVIDIA will be reinstating the restriction in new downloads of the beta driver and in the WHQL build of these drivers.

Update: NVIDIA tells us that they will also be "fixing" the 257.15 beta driver on their site, so new downloads of that driver will have the restriction in place

Yes, this is a bug in the latest build of PhysX that was packaged with the driver. We'll be fixing this issue ASAP - the WHQL driver launching in early June won't have this issue. -NVIDIA

For those of you heterogeneous GPU users out there looking to use PhysX, there is some good news that can be salvaged from this however: this won't change the fact that previously downloaded copies of beta drivers lack this restriction. With these drivers you can still have heterogeneous GPUs with PhysX without modifying NVIDIA’s drivers, but you’ll be stuck on these drivers for the time being.