Introduction

In our original PhysX Performance with GeForce article we highlighted the performance of NVIDIA’s PhysX API running on GeForce GPUs ranging from the GeForce 9600 GT all the way up to the latest GeForce GTX 280. For comparison purposes we also included scores with the same PhysX apps running on the CPU to highlight the performance improvement GPU-based PhysX can bring.

In those tests we generally found that PhysX apps ran around three times faster on the GPU in comparison to the CPU, although the exact amount varied depending on the game being tested – some cases were up to four times faster.

After seeing the results, we received numerous requests from readers asking us to include scores with AGEIA’s PhysX PPU. Many of you were curious to see how the PPU stacked up to today’s GPUs when it came to PhysX performance.

To accomplish this we dusted off our old PhysX card manufactured by BFG, and plopped it into an open Core 2 QX9650 testbed we’d already had setup. Surprisingly enough, the board still ran like a charm! We then proceeded to install the PhysX apps and came up with another custom demo for Unreal Tournament 3 testing taken on the heat ray map under similar conditions (our original demo used for testing was deleted when we wiped the testbed’s hard drive). Once again we used the gravity gun’s secondary fire mode exclusively to send objects flying throughout the map. Our tests with Warmonger and Nurien use the standard built-in benchmarks that ship with each app (we actually use FRAPS to record Nurien scores, as the built-in fps results are inaccurate). The MKZ alpha doesn’t seem to work with the PPU at the moment. Every time we tried to run the benchmark, the game crashed to the Windows desktop.

So how did the PPU fare against the GPU? First let’s take a look at UT3:



As you can see, going from the CPU to the PPU netted us a gain of roughly 2.5X. All of the cards generally top out around 32-34 frames per second with the PPU handling physics, versus 13 fps with CPU-based PhysX. The GeForce GPUs then run 16% faster than PPU-based PhysX in UT3.

Nurien

If you recall our original article, the cloth simulation in Nurien wasn’t as demanding as the physics calculations in the other games we tested, and thus we saw slimmer gains in favor of GPU-based PhysX. Based on this, we expected PPU performance to be at least on par with GPU PhysX performance, if not better since we’re running dedicated PhysX hardware. Surprisingly enough however this wasn’t the case:



We re-ran the tests multiple times to ensure that our PPU results were accurate. Each time though the scores remained pretty consistent. The PPU just wasn’t scaling beyond 36 fps, an improvement of 1.5 times for the GeForce boards over the CPU, while the Radeon cards ran about 14% faster with the aid of the PPU.

The GeForce PhysX setup still ran over 20% faster than the PPU setups though.

Of course, Nurien is pre-release alpha software. It was probably never designed with AGEIA’s PPU in mind. This isn’t the case for our next app, Warmonger…