Published in Reviews
Nvidia helps the HD 5870 beat the GTX 285 in PhysX
Review: With 9800GT as dedicated PhysX card
Two years ago, Nvidia bought Ageia and established itself as the leader on the field of gaming physics technology. Unfortunately, while the future of gaming was never questioned, the adoption of PhysX technology by software developers hasn’t been an overnight feat. In order to accelerate the matter, Nvidia developed Compute Unified Device Architecture (CUDA) which made PhysX a feature on all CUDA-supporting graphics processors, meaning series 8 and newer. This was quite an important move as it allowed millions of Geforce owners to enjoy physics effects, but unfortunately for the company the number of available PhysX supporting titles is still pretty low. The situation is improving though and more and more games include PhysX, and the reason is more than evident after even a few minutes of PhysX gaming.
Of course, all this visual goodness doesn’t come without cost and PhysX requires some serious muscle to run. This job is traditionally done on the CPU whereas the GPU is in charge of drawing it on screen. With Ageia’s technology, Nvidia moved some of this intensive load to the GPU, which is of course much faster in this respect. However, calculating physics on the GPU also makes rendering graphics harder and framerates will usually duck significantly unless you’re a proud owner of one of Nvidia’s fastest cards. Nvidia solved this problem by advising users to utilize a dedicated PhysX processing graphics card. This card thankfully does not have to be a pricey, fast card but rather any Geforce graphics card with a CUDA supporting GPU.
So, if you for instance own a Geforce GTX 260, you can use a cheaper Geforce such as 9600GT to handle your PhysX calculations. In practice, it’s as simple as choosing the dedicated PhysX card in Nvidia’s driver.
Unfortunately for some, Nvidia kept the technology to itself, so Radeon cards aren’t supported, but that doesn’t mean that it’s impossible. PhysX support is automatically blocked upon detection of Radeon cards, but luckily, there are workarounds and various forums have been pretty loud about it for a while.
We recently included Batman: Arkham Asylum game in our gaming benchmarks, and while the game supports PhysX effects, we usually use only the results we got without PhysX. The reason hides behind Radeon cards which don’t score a good enough framerate when PhysX is on, so there’s no point in comparing them. Since it’s not very fair to exclude Nvidia’s strengths from our tests and our trusted readers have requested Radeon results with PhysX effects on, we decided to do it. So, we embarked on what would many fans of green and red camps probably called sacrilege – we assigned a Geforce card to handle PhysX and as our primary card we used a Radeon.
You can find out how to install the drivers and the PhysX patch that works around Nvidia’s restrictions here and here, but there’s plenty of forums that are pretty vocal about the lack of Nvidia’s official support for this symbiosis with Radeon cards. Note that we didn’t manage to do this with Nvidia’s latest Forceware 196.21 drivers and we had to revert to Forceware 191.01.
As you can see from the following results, the HD 5870 is a great card for playing Batman: Arkham Asylum but, naturally, only if you’re playing the game without PhysX effects. Upon turning PhysX effects on, the HD 5870 made gaming impossible whereas the GTX saw the frame count sliced in half. GTX 285 is the fastest single-GPU Geforce so despite the hefty PhysX processing needs, it still retains enough punch for a playable framerate at 2560x1600.
The significance of a dedicated Geforce graphics card for physics calculations is evident from the following table. Thanks to the dedicated Geforce 9800GT, Radeon HD 5870 managed to score over 100fps even with PhysX effects set at high, and impressively enough, not even the GTX 285-9800GT combination managed to beat this. After assigning a dedicated 9800GT card for PhysX, we couldn’t change antialiasing with our Radeon card so the tables feature same results in scenarios with and without antialiasing.
We also included FluidMark results in our testing and they clearly show that the HD 5870 depends on the 9800GT for physics calculations. Without the dedicated Nvidia card, HD 5870 scores 1575 o3Marks but the result soars to 9714 o3Marks when we include the 9800GT dedicated card.