CPU Benchmarks: PhysX Enabled
We were somewhat puzzled by the results we saw when we benchmarked the Radeon cards at the different PhysX settings. Strangely enough, the minimum and average frame rates stayed static between the Normal and High PhysX settings, even though the GeForce cards showed a large performance hit for the minimum frame rate.
We therefore ran a couple of tests using Radeon cards with PhysX enabled at different CPU speeds:
This would seem to make sense, because the frame rates go down with lower clock rates. Here's the weird part, though. We took note of CPU utilization during a specific part of the game benchmark, a PhysX-heavy segment where a guard is walking through smoke. Results were repeatable and consistent over several runs:
Why is CPU utilization lower when PhysX is enabled? And why is CPU utilization so low at all? If the CPU is bottlenecking the PhysX calculations, shouldn't the increased load be pushing the CPU to its limits?
Maybe we can make more sense of this if we look at how the CPU is handling threads:
Rather than clearing things up, the results of this testing have only left us more puzzled. We can recall that the PhysX API is supposed to be optimized for multiple threads, yet on the Core i7, only a single thread seems to be stressed when PhysX is cranked up. We're trying to get clarification from the developers at Rocksteady about this phenomenon--it's almost as though the game is artificially capping performance at a set level, and is then using only the CPU resources it needs to reach that level. On the Core i7, PhysX is using fewer resources than it does on the Phenom II. This would make sense if there was an artificial performance cap, as the i7 has shown to outperform AMD's architecture. However, the benchmarks show us a correlation between actual performance and raw CPU speed on either CPU.
Great article, really informative. Looking forward to hearing back from the devs regarding CPU usage.
cant wait to try it.
This is a Games for Windows Live product. Or On-line account Evil DRM malware tracking software required.
I really want to play this; but alas I cannot buy it
Wow..I didn't expect GT 220 is a good dedicated Physx card,.. Off searching in eBay LoL
Looks to me like nVidia had this game rigged to better benefit it's cards, note the decrease in CPU involvement as the physX options are cranked up.
That is why Arkham Asylum should be Game of the Year - It is a work of art!
Would a setip with an Nvidia card for PhysX and an ATI card for graphics work? Noob question i know :-P
Would a setip with an Nvidia card for PhysX and an ATI card for graphics work? Noob question i know :-P
I don't think it's a daft question - there was a= bit of news or an article a short while back saying that nvidia had set something so that physX couldn't be used if there was a non-nvidia card handling the graphics (or something like that). I was going to raise the same question as to 'can the GT220 be used as a physx card regardless of the main GPU?' as I can't remember much about the other article.
I play this game using 2 8800GTs, one for graphics and one for the physx (on high).
All settings on max and res at 1080p
Benchmark gets about 40fps, played the whole game though with no noticable slowdown.
The physics were locked down because PhysX is an nVidia product (no one supported AGEIA dedicated cards when the original company (Ageia) was making the entry to the market),as some profit based companies would still use havok at that times and not see the huge potential of the PhysX of AGEIA, it's only reasonable that now that Ageia merged with nVidia, they want to make profit by selling their graphic cards.
The second reason, I think, is that the PhysX wouldn't even try to use the CPU for Physics for performance related issues (smooth frame rate in every case scenario rig).
As I recon, AMD is making a move in the Physics with the 5th serie.
Just wait and see... Again