Hoping to grab a new Radeon HD 5850 and use an old GeForce to accelerate PhysX effects in games? Too bad; newer Nvidia drivers won't let you use hardware PhysX acceleration unless you're using a GeForce for graphics, too.
A member of the NGOHQ forums first broke the story a few weeks back, quoting the following explanation from Nvidia's Customer Care department:
Physx is an open software standard any company can freely develop hardware or software that supports it. Nvidia supports GPU accelerated Physx on NVIDIA GPUs while using NVIDIA GPUs for graphics. NVIDIA performs extensive Engineering, Development, and QA work that makes Physx a great experience for customers. For a variety of reasons - some development expense some quality assurance and some business reasons NVIDIA will not support GPU accelerated Physx with NVIDIA GPUs while GPU rendering is happening on non- NVIDIA GPUs. I'm sorry for any inconvenience caused but I hope you can understand.
The limitation applies to GeForce 186 and newer driver releases. Also, it mainly concerns folks running Windows 7 (either in pre-release form or otherwise), since Windows Vista's Windows Display Driver Model 1.0 specification doesn't support running multiple GPUs with different drivers simultaneously. Microsoft removed that limitation in Windows 7's WDDM 1.1 spec.
Since we're attending the ongoing GPU Technology Conference in San Jose, California, we brought up the matter with Nvidia. Ujesh Desai, the company's GeForce General Manager, confirmed the limitation, but he blamed technology and compatibility hurdles for the move. He also noted that Nvidia would rather not provide validation and support for its competitors' products.
The second claim is understandable, but the first sounds a little hard to believe. After all, members of the NGOHQ forums claim using Nvidia cards for PhysX in Radeon-powered systems works just fine with pre-186 drivers. We'll try to poke around for more details. Stay tuned.