http://developer.nvidia.com/object/apex_dev.html

NVIDIA APEX for Developers

Does NVIDIA APEX require a NVIDIA GPU (or PhysX Processor (PPU))?

No. NVIDIA APEX actually scales to multiple different environments, both with hardware acceleration and without. NVIDIA APEX is tuned for multi-core setups; single-core setups; and for current and future iterations of the NVIDIA GeForce GPU.

說穿了就是保留以前PhysX的Multi-core CPU支援，所以有multi-core CPU，執行AGEIA PhysX SDK的遊戲就能夠受惠。