Mafia 2 PhysX: Overclocking Nvidia's official PhysX setup
We uninstalled all the drivers and driver cleaned everything to make sure no modified or ATI drivers were left hanging in the system, before starting again with the two Nvidia cards, 258 WHQL drivers and now a 4.2GHz 6 core CPU.
Mafia II Benchmark - GTX 460 OC
1920x1080, 0xAA, 16xAF, in-game benchmark
GeForce GTX 460 768MB (+ GTX 275 PhysX)
GeForce GTX 460 768MB(+ GTX 275 PhysX) 4.2GHz OC
The result is very interesting and against our expectations. We can only conclude (without a more powerful graphics card or another GTX 460 on hand to confirm) that we've actually become GPU limited again as there's no particular increase in average frame rate.
Click to enlarge
From out testing here we can conclude that PhysX is still very much suited to either a dual purpose render/PhysX card or, ideally, a dedicated PhysX card. CPU PhysX performance just doesn't come close, even with a heavily overclocked six-core monster.
Nvidia is due for a big PhysX overhaul and launching PhysX 3.0 really can't come soon enough. This update is rumoured to give better performance and more effective CPU threading instead of just requiring mountains of MHz. As we've seen, all the available CPU cores are currently not being used as much as possible,. This of course suits Nvidia and we realise the performance gulf helps sell the GPU PhysX argument.
There's no doubt that adding an extra graphics card gives a massive leap in FPS: from unplayable to playable, making CPU PhysX all but a non-option in Mafia 2, whatever your graphics card. It's not a great situation for ATI customers but in Mafia 2 it's clearly a case of using either GPU accelerated PhysX or no PhysX at all. The performance drop resulting from CPU PhysX is enormous.
Having played the game with a GTX 460 and dedicated GTX 275 PhysX card most of the time the performance is fluid and natural, with the additional effects adding to the gameplay experience. However, while 'most of the time' is great, having PhysX on does occasionally cause a massive drop in performance during PhysX heavy parts of the game. One particular firefight in a brewery becomes unplayable until you drop the APEX PhysX setting from high to medium. Personally speaking there's not a huge visual difference between medium and high, but obviously the additional fps from slideshow to smooth more than makes up for it. However, we'd certainly be a bit miffed if we'd shelled out for the extra dedicated PhysX card only to find it fell on its face in the first heavy scene when PhysX is set to high.
The question is, is it worth shelling out for an extra PhysX card to play Mafia 2? PhysX effects remain a purely visual addition to a game and while Mafia 2 makes better use of it than we've seen previously from titles like Batman: Arkham Asylum, is it worth the cost of the additional hardware just to run one game with the shiny turned on? From what we've seen, it's certainly worth using an ageing 8-series of GTX 2xx series card for PhysX if you already have one, but so far as buying a card expressly for PhysX or running an ATI/Nvidia Hybrid setup goes it might be that Mafia 2 is one game and you can live with turning PhysX off.