Re: How much GPU does PhysX use?
Physx never announced the performance of their chip so its hard to say, if they are using the same kind of workloads. However, they were using 128mb of ram on their boards so assuming they do the same work, I would imagine you're losing 128mb or so. Unless they are using system ram, but I dont know if that would be fast enough, seem like Physx boards used fairly fast GDDR3, PCIe bus probably wouldnt be able to keep up the same rates.
This all assumes they are doing a similar amount of work.