Something else I'm not sure you're aware of. When dedicating PhysX to CPU in the Nvidia Control Panel it sets the PhysX setting in game to normal. You can't set it to high. It will stay on normal until you set PhysX back to either auto or in some manner using a GPU in the Nvidia Control Panel. Then you have to reset the PhysX to High in the game options and restart the game. I bring this up because your SLI TITAN FPS look like that might have been run with PhysX on normal instead of high. Also it reveals, that since the game forces PhysX to normal when using the CPU, the performance for even reduced PhysX on the CPU is terrible as you indicated.
Thanks! I will check this later tonight when I get back to my home office. Though, I'm pretty sure I checked the settings on the last run I made (Titan standalone) and it was still set to HIGH. But I'll check it with CPU and all and such and will report back.
If you compare the Titan StandAlone to the Titan SLI, they are almost identical. The roughly
15% increase in going from a single GPU to 2-way SLI GPUs matches what others have posted online. So, I'd say it was an accurate test.
Lastly, each "run" was at least 2 runs in each configuration ran back to back. And then a reboot when the configuration changed. I mention this because on some runs when there was a significant difference between the back to back runs, I ran it 3 or 4 times with reboots until I got an accurate test. For example, the Titan w/CPU PhysX was all over the place. I found out that if I closed Google Hangout, it was far more reliable. But, it me like 6 runs until I got a consistent back-to-back run (and the one posted above is actually the best out of all runs).
But I'll verify and will post back.
HeavyHemiThis line is a bit confusing as related to your graphs: "SLI was always disabled when using the 2x Titans. I used the PhysX Settings to designated either Titan GPU1 or Titan GPU2 as the PhysX engine, with GPU2 checked off as "Dedicated to PhysX." Did you run with the TITANS in SLI with PhysX on auto with just the two TITANS installed?
I can see how that is a bit confusing now. Thanks again. I'll try to re-word it in a bit.
When I first wrote that line, I had not made a Titan 2-Way SLI run. All tests were purely a single Titan, plus whatever I was messing with for the PhysX (a 2nd Titan vs GTX460 vs CPU vs None). That last one, "None", is what I meant by manually setting it to GPU1.
When I did the Titan w/Titan PhysX runs, I manually designated GPU2 as the PhysX card and checked the box for "Dedicated to PhysX" - there was no SLI enabled.
That checkbox, "Dedicated to PhysX" is not available when you are using the primary GPU as PhysX manually set. You can only check it on other GPUs.
And just for completion of all settings:
I did not just take these screenshots. I took each screenshot, including in the OP, when I made the change. I also rebooted after each change to ensure no funkiness with the Nvidia drivers. This is why some monitors are flipped around as I was tring to get Surround working earlier on a single GPU without success when I had two identical GPUs in the system.
So, it is confusing because I was trying to encompass all of that information in a single sentence. But you are right, there are a lot of specifics to each test run.
The ONLY time I left the PhysX set to "Auto" was for the Titan 2-way SLI runs. All other times, I manually set it (and even captured screenshots of each setting). Sadly, I didn't grab a screenshot of that setting as, well, that's the default when you enable SLI anyways - set to Auto, and it designated GPU2 as the PhysX engine.