try using older version of DDU .... for dedicated PhysX use the PhysX card or 750/780 already should have one integrated

SLi won't work if GPU's are not same spec or close (especially under XP).

ediflorianUS wrote on 2023-06-04, 10:55:

try using older version of DDU .... for dedicated PhysX use the PhysX card or 750/780 already should have one integrated

SLi won't work if GPU's are not same spec or close (especially under XP).

Windows XP has no support for SLI above Geforce GTX 670 series cards, which may be whats causing issues with the 700 series cards here, the other issue is that the 750ti is a Maxwell based card and the 780 is a Kepler based card this may be a sore point for XP as there would be two different driver sets required. (Never tried this kind of setup myself but I know it works fine in Windows 7 and up, but XP is an odd beast and may not like mixing Maxwell drivers with Kepler)

https://nvidia.custhelp.com/app/answers/detai … t-in-windows-xp (Might be possible there are modded drivers out there but no idea if they work or not)

With a 780 I have no idea why the OP wants the 750ti as the physx card . .the 780 can handle that with zero performance loss to raster, so little to no point in bothering with the 750ti here.

I just wanted to experiment and see if I get more FPS in FluidMark, with the 780 alone or with the 750 Ti dedicated to PhysX.
I can swap out the 780 for a 960 to see if that makes a difference.

Trashbytes wrote on 2023-06-04, 14:27:

Windows XP has no support for SLI above Geforce GTX 670 series cards, which may be whats causing issues with the 700 series cards here, the other issue is that the 750ti is a Maxwell based card and the 780 is a Kepler based card this may be a sore point for XP as there would be two different driver sets required. (Never tried this kind of setup myself but I know it works fine in Windows 7 and up, but XP is an odd beast and may not like mixing Maxwell drivers with Kepler)

Windows XP has no SLI support for any Kepler based GPU. That includes GTX 670. Last family of cards that has support is Fermi, i.e. GTX 590 or lower. But this has nothing to do with separate GPU for PhysX anyway.

The Serpent Rider wrote on 2023-06-04, 15:44:

Trashbytes wrote on 2023-06-04, 14:27:

Windows XP has no support for SLI above Geforce GTX 670 series cards, which may be whats causing issues with the 700 series cards here, the other issue is that the 750ti is a Maxwell based card and the 780 is a Kepler based card this may be a sore point for XP as there would be two different driver sets required. (Never tried this kind of setup myself but I know it works fine in Windows 7 and up, but XP is an odd beast and may not like mixing Maxwell drivers with Kepler)

Windows XP has no SLI support for any Kepler based GPU. That includes GTX 670. Last family of cards that has support is Fermi, i.e. GTX 590 or lower. But this has nothing to do with separate GPU for PhysX anyway.

Yes but I was pointing out the lack of SLI support, the person I replied to didn't seem to be aware of XP not having SLI support for anything above Fermi, also why I linked back to a nVidia post about it, people want evidence.

As for OPs issue, driver conflicts would be my guess, switching the 750ti to a 760 would likely resolve the problem.

I replaced the 780 with a 980 Ti and the 750 Ti with a 960, and the same thing happened. It must have nothing to do with the architecture of the installed GPUs matching each other, but is probably caused by the lack of SLI (and all multi-GPU) support for Kepler and newer GPUs.

retroboy87 wrote on 2023-06-09, 14:23:

I replaced the 780 with a 980 Ti and the 750 Ti with a 960, and the same thing happened. It must have nothing to do with the architecture of the installed GPUs matching each other, but is probably caused by the lack of SLI (and all multi-GPU) support for Kepler and newer GPUs.

I get why you wanted a single GPU for Physx but the 780 or even the 980ti can handle that with zero performance loss even as a single GPU, Physx really isn't that demanding for modern GPUs and the architecture of Kepler/Maxwell would only help even further due to being optimized for such calculations via CUDA. (Cant remember if its doing it via CUDA or another method but I assume CUDA as it would be fastest)

I own an original Ageia PCIe Physx card and even an 8800 GTX will happily run circles around that card which was designed specifically for Physx, so I can imagine a 780 would totally max Physx out regardless of what the rendering pipeline was doing at the time.

I would imagine at some point the CPU itself would be come the limiting factor for Physx calculations as it uses heterogeneous setup where the GPU is handling all the heavy lifting but also employs the system CPU for the less demanding calculations.

I just wanted to see if I would get a performance boost in XP with a dedicated PhysX card.
Before I upgraded from my 980 Ti to a 2070 on my main Windows 10 (now 11) PC, I used a GTX 1650 as a dedicated PhysX card and got a 20FPS boost (65 FPS to 85 FPS) in FluidMark with max settings at 1080p.

retroboy87 wrote on 2023-06-09, 14:42:

I just wanted to see if I would get a performance boost in XP with a dedicated PhysX card.
Before I upgraded from my 980 Ti to a 2070 on my main Windows 10 (now 11) PC, I used a GTX 1650 as a dedicated PhysX card and got a 20FPS boost (65 FPS to 85 FPS) in FluidMark with max settings at 1080p.

You could grab a pair of cheap GTX 570s or a 570 and 580 and try again, XP has full support for SLI with Fermi cards, once you have gotten results you could then just sell the cards if you dont need them.

At the least it would answer the question.

Trashbytes wrote on 2023-06-09, 14:50:

You could grab a pair of cheap GTX 570s or a 570 and 580 and try again, XP has full support for SLI with Fermi cards, once you have gotten results you could then just sell the cards if you dont need them.

At the least it would answer the question.

Nah, I'll stick with Kepler/Maxwell. I want DisplayPort 1.2 for dual booting with Windows 10.

retroboy87 wrote on 2023-06-09, 14:59:

Trashbytes wrote on 2023-06-09, 14:50:

You could grab a pair of cheap GTX 570s or a 570 and 580 and try again, XP has full support for SLI with Fermi cards, once you have gotten results you could then just sell the cards if you dont need them.

At the least it would answer the question.

Nah, I'll stick with Kepler/Maxwell. I want DisplayPort 1.2 for dual booting with Windows 10.

heh, fair enough

Its a shame no video had to screw over XP the way they did, its not like XP couldn't handle SLI with Kepler and Maxwell, same with nuking GTX 970, 980 and Titan X support int he drivers forcing everyone to mod them to get it back. Though nVidia doesn't have the best consumer record, always doing shady shit regardless of how good the actual hardware is.

I might actually have bought a 4000 series card if they didn't jack prices up to stupid levels, will have to eventually as they seem to be on the locking features out for cards more than capable of them path again.