Good Physx Bench for GTX780 + GTX650

[gun5l1ng3r]

I have been reading a few threads regarding a dedicated Physx card and had to try for myself to see how one would work with my GTX780.

I only had time last night to run Fluidmark which I found through Google as a Physx benchmark. The odd thing is that my GTX780 seems to run the benchmark much faster without the GTX650.

No matter what settings I seemed to use (2560*1440 w/ 120,000 particles and multithreaded turned on or the 1080 preset)

At my custom settings of 2560*1440 my GTX780 alone global score was ~500 & 41fps and with the GTX650 added in for Physx, the global score drops to ~330 & 29 fps. No settings were changed between these two runs...

My system does detect the 650 and when running the above tests, it gets to about 75% usage and my gtx780 stays at about 80% usage.

The OSD in Fluidmark for the 650 shows "THROTTLING -506 mhz" even though Precision X shows it at the stock 1057mhz...

When running the tests with just the gtx780, it goes to about 99% usage...

I am still new to the whole benching world and havent had a chance to bench this setup in any games yet...how would I go about doing that? FRAPS? Does Borderlands 2 have a bench run available?

Is the GTX650 just not powerful enough for a GTX780? Some say the clock speed on the dedicated card is more important than core count, while others say that core count is crucial? A GTX650ti has many more cores and might be better suited for the gtx780...Any thoughts?

Or is it looking like a gtx 760/770 might be needed to match the power of the 780 to see any benefit?

My rig:
i7 920 @3.6ghz
EVGA X58 Sli
EVGA GTX 780 SC ACX @ 1202mhz
EVGA GTX 650 1gb @ 1057mhz
Seasonic X Series 850w
Corsair Force GT 128GB
WD Velociraptor 1TB

 

[Carfax83]

The OSD in Fluidmark for the 650 shows "THROTTLING -506 mhz" even though Precision X shows it at the stock 1057mhz...

The reason why it's throttling is because the PhysX workload isn't great enough for it to run at full speed.

Have you tried adjusting the settings, ie number of emitters and particle count?

When running the tests with just the gtx780, it goes to about 99% usage...

Because the GTX 780 is doing both rendering and PhysX at the same time.

I am still new to the whole benching world and havent had a chance to bench this setup in any games yet...how would I go about doing that? FRAPS? Does Borderlands 2 have a bench run available?

Metro Last Light, Arkham City and Mafia 2 have PhysX benchmark runs integrated with the games. BL2 doesn't have one though.

Is the GTX650 just not powerful enough for a GTX780? Some say the clock speed on the dedicated card is more important than core count, while others say that core count is crucial? A GTX650ti has many more cores and might be better suited for the gtx780...Any thoughts?

OK this is how it works. A dedicated PhysX card works best when:

1) The primary rendering GPU's workload is too great for it to run both 3D and PhysX at the same time without compromising performance.

2) The dedicated PhysX card can handle the PhysX workload by itself.

In the first scenario, a GTX 780 could conceivably run PhysX much faster than the GTX 650 dedicated card, as long as it's not being overtaxed by having to render 3D graphics.

So if you're playing at 720p for arguments sake, your GTX 780 would have plenty of spare power available so that you wouldn't even need a dedicated PhysX card.

If on the other hand you play at 1600p, then a dedicated card could definitely come in handy because your GTX 780's graphics workload is going to be much higher.

In the second scenario, if the PhysX workload is too great for your dedicated PhysX card, then it will drag down the performance of your entire system.

Or is it looking like a gtx 760/770 might be needed to match the power of the 780 to see any benefit?

Personally I recommend a GTX 650 Ti for a dedicated PhysX card. It has twice the cores of the GTX 650, which is what PhysX performance relies on the most, and it doesn't cost that much more than the base GTX 650.

A base GTX 650 is great for current PhysX games though, so you should have no problems with it in BL2, Metro Last Light, Batman Arkham City etcetera.

In future games though, that may change.

BTW, a faster CPU would definitely help you out quite a bit..

 

[gun5l1ng3r]

BTW, a faster CPU would definitely help you out quite a bit..

Do you think a faster CPU would help even though I am offloading the Physx to the 650?

 

[Carfax83]

Do you think a faster CPU would help even though I am offloading the Physx to the 650?

I'm not suggesting you use your CPU to run hardware accelerated PhysX. I'm just saying a faster CPU would definitely help your system performance.

Whenever you have multiple GPUs in your system, a faster CPU helps because it's the CPU that's ultimately orchestrating all of it. Similar to how a faster CPU increases SLI performance.

If you could overclock your CPU another 400mhz, that would help out a bit I'm sure.