Mr. Mister said:
Or maybe "arguably" because the game detects the PhysX card and enables dozens of particle effects and fluid areas that otherwise wouldn't exist in the game, calculating them with a marginal slowdown while at the same time running the game with a physics detail that would slow the computer down 400% if it didn't have a PhysX card. Saying that adding a PhysX card slows games down is a very flat way of looking at it, it's like saying adding a 7900GTX and playing FEAR is inferior to running Quake II on a 9800 Pro because the latter gets a better framerate than the first, disregarding that FEAR is pushing realtime light and shadow effects while Quake II is barely 3D.
Indeed. However, the benchmarks I saw suggested with full effects the game would be borderline playable, and the eye-candy -- and that's all it added in this case -- in the movie wasn't that big an improvement, so it seems rather pointless based on that example. I am however willing to accept that the support for the card was likely added very late in the dev cycle and thus the engine's support could be rather sub-optimal for the title in question (GR:AW).
Adding in the card should be pretty much transparent in the sense that it shouldn't drag the rest of the system down, which this obviously does, especially when the current PhysX card is the only one -- it's not a moving target like supporting the huge capability gulf between, say, GMA950 and GeForce MX cards at one end and the latest nVidia 7900GX2 or ATI 1950-range cards.
It shouldn't be about rendering "more", it should be about improving realism -- because rendering more is still hitting the GPUs hard, and if they don't have power to spare, adding more into the mix isn't helping...
It's also not really akin to Q2 vs FEAR, which would be several orders of magnitude in a very visible sense. It's more like changing the detail level in FEAR from low to high and comparing things that way.
Either way, what I've seen thus far suggests that the PhysX card isn't terribly impressive, especially considering the price-tag. Maybe some newer games will make better use of it, or maybe it's the hardware implementation itself that's the problem...