Try it in your system. You are the only one that can justify if it is worth it or not.

well the only way to know for sure is to test it :)
 
use this physx benchmark and tell us what did you see :D
 
http://www.geforce.com/wh...11-and-physx-benchmark

I don't know why your PLA Link is dead but here is the real link http://www.geforce.com/whats-new/articles/put-your-system-through-its-paces-download-the-pla-directx-11-and-physx-benchmark
 My test with a GTX 1080 FTW and a 980SC with Physx set to high were:
 
1080 only
Avg 82.9 High 130.0
 
1080 with 980
Avg 112.2  High 158.2
The Utility did not give a low
 
From this it looks like on physx enabled game the 980 gives a 26% increase in Avg frames and 18% increase in Max Frames. Decide for yourself if it is worth it to keep it in your system. I personally don't see the harm since if it cant be used it just idles at 135mhz sipping very small amounts of power.
 
 
Edit Forgot to put in bench was DX 11 High settings, 1440p, FXAA High, Dynamic Shadows on, Texture normal, and post processing on.

I am concerned about the power requirement for the additional card. I've used a few power estimation tools online and they say the maximum draw should be around 840W (with both cards), but my PSU is only 850. The tools appear to add ~190W for the 970.

EVGATech_JosephL
Hello Peirs123 and welcome to the Forums!
 
It really depends on the application/game you are using. You will see a performance increase but in several scenarios this may only be a 1 FPS difference. Certain games like GTA V have shown to take a little more advantage from a dedicated PhysX card. As scarlet-tech mentioned, it will really be up to you when testing.

GTA V doesn't use PhysX at all.
 

Piers123
As the title says, I have a MSI GTX 970 Twin Frozr card sitting in a box.
 
Is it worth using it as a PhysX card? If so, would my current PSU support it (specs. in signature)?
 
Note: I play in 3840x2160 where possible with settings adjusted to provide 50-60 FPS.

 
Too answer your question more specifically, the Batman series, Borderlands 2 and the Prequel, Mafia II and Fallout 4, and the Metro Series etc etc, will see significant gains and will help make those titles playable with higher settings with higher FPS. Of those I listed, Fallout 4 and the Metro series are not going to run at 60 FPS all the time at 2160 with max quality settings. However your can max it out at 1440p including the highest in game AA for Fallout 4 and keep a min of 60 FPS. Most games don't use PhysX especially GPU accelerated PhysX. So, whether or not it is useful for you, depends upon what you play.

I've installed the 970 and... appear to see a dip in performance. Fallout 4 runs at 60 FPS in 99% of areas with a mix of ultra and high settings at 2160. Benchmarks all return lower scores with the 970 set as a dedicated Physx card.
 
Any ideas why?

A couple things to look at.  Check in the NVCPL and make sure Vsync isn't enabled globally.  Also make sure to set PhysX to auto letting the application decide which to use for Physx.  Keep in mind, only games or programs that actually use & support PhysX will use the 970.
 
Here's a link you may find useful if you haven't already seen it  >>  http://www.geforce.com/games-applications/technology/physx
 
 
 

Your 970 is using resources especially, even if it isn't active, because the gpu has to relate if it needs to work or not. That is probably why your scores drop a little.

Piers123
The following have been run at maximum possible settings and at 3840x2160
 
PLA Benchmark
GTX 1080 + 970 (dedicated Physx)
AVG: 60.0
MAX: 62.2
Note: FPS remained stable throughout test.
 
GTX 1080 only
AVG: 51.8
MAX: 65.9
Note: FPS dropped down to 29 FPS in PhysX-heavy scenes.
 
Unigine Benchmark 
GTX 1080 + 970 (dedicated Physx)
AVG: 19
MAX: 38
 
GTX 1080 only
AVG: 29
MAX: 60
 
 
Fallout 4 (gameplay)
GTX 1080 + 970 (dedicated Physx)
AVG: 60
 
GTX 1080 only
AVG: 60
 
TimeSpy 
GTX 1080 + 970 (dedicated Physx)
SCORE: 7438
GPU SCORE: 7862
 
GTX 1080 only
SCORE: 7455
GPU SCORE: 7906
 
 
I'm unsure what to make of this - whether the additional heat and power justify the results. Some tests are worse with the 970 acting as a dedicated PhysX card.

Bringing back this tread (yay). Gears of War 4 is coming, and apparently it's supposed to include Nvidia PhysX.... Soooo. to add more to the discussion, what I think a PhysX card is really supposed to do is:
keeping the system from tanking and falling under a certain FPS. Forget the fact of "adding extra FPS", we are looking at the wrong idea that way. The idea behind the PhysX is of course keeping the system running a stable FPS through the gaming period. I wouldn't buy a phsyx card though. If you have it, great, use it.

veganfanatic
For the record I have one of the original PhysX P1 cards, then some corporation said up your's 
Easy to switch to Radeon and ignore the nonsense
 
The aforementioned corporation does not want to be a 'mere' PhysX card either
 

I have an original Ageia physics card, which was bought out by Nvidia. Does that count?

stalinx20

veganfanatic
For the record I have one of the original PhysX P1 cards, then some corporation said up your's 
Easy to switch to Radeon and ignore the nonsense
 
The aforementioned corporation does not want to be a 'mere' PhysX card either
 

I have an original Ageia physics card, which was bought out by Nvidia. Does that count?

Nope, no driver support so no respect
 

recall the damages arising from 196.75 

I have seen recent motherboards with no PCI slots at all. The one I have has 2 PCI slots and one PCI Express x4 slot available with a Wi-Fi card and video card installed.
 
here is my old page on video card overheating
 
The picture of the popped Teapo capacitors meant a quick demise to my video card