Can someone please explain PhysX to me (or link me good sources)?

[Wolfgang]

So the background is that recently two games that I play (Euro Truck Simulator 2 and American Truck Simulator) will change their physics engine from Bullet to PhysX in the new big update. However, I still don't really understand much of it so that is why I ask here.
Basically what I would like to know is:
- Does PhysX run on GPUs other than Nvidia too? If it does, is there a performance difference?
- I read that CPU PhysX is pretty bad on the performance. Is that only the 32bit version or is that also true for the 64bit version?
- What exactly does the "CPU dispatcher" mean? Background is this part of the log from the game:

00:04:05.587 : [physx] @0: Created foundation version 1.0.0.
00:04:05.587 : [physx] @0: Created physics version 3.4.3.
00:04:05.587 : [physx] @0: Initialized extensions.
00:04:05.587 : [physx] @0: Created CPU dispatcher with 2 threads and logical CPU affinities:
00:04:05.587 : [physx] @0: CPU          0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15
00:04:05.587 : [physx] @0: thread   0   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *
00:04:05.587 : [physx] @0: thread   1   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *
00:04:05.587 : [physx] @0: Created convex cooking.

Thank you in advance.

[_I_]

physx can either run on cpu or nvidia gpu (8000gt to rtx4000)

if the cpu has a few more cores/threads than the game needs, on cpu will be fine
or gpu is fine the gpu is not at 90+% usage

test and see how well it does for the games
or just leave it to auto in nvidia control panel

as for game specific stuff, ask in the games forums

[Bad 💀 Motha]

GPU PhysX requires NVIDIA GPU, RTX 40 series or older.
However some games still require PhysX to be installed regardless of your GPU; if you have Intel or AMD GPU, PhysX will be done by CPU.

[Chaosolous]

It's just a physics system used by some developers.

If you have a normal PC, it shouldn't impact your performance much.

It's a pretty standard physics system, or rather, it used to be. IDK how popular it is now. Used to be used in pretty much everything though.

[Monk]

The majority of Physx still runs on 50 series, only those running on 32 bit instead of 64 bit dont.

[Wolfgang]

Okay, so running PhysX on the CPU isn't directly a really bad thing, right?

[_I_]

Wolfgang の投稿を引用：

Okay, so running PhysX on the CPU isn't directly a really bad thing, right?

on the older 2-4 core cpus, it would hurt performance,
but newer cpus have more cores than the games need, and are much faster and can handle the extra load for physx with no problems

with the older systems, adding an nvidia gpu for dedicated physx did help with some, but a higher end single gpu could do physx and rendering better than adding a lower end physx gpu

[xSOSxHawkens]

Unless these two games are updating to FP64 Physx then the devs are screwed.

NV just killed off 90% of PhysX support in their most recent release of the RTX5k cards.

People who play games that actually make heavy use of PhysX are having to put in second GPU's to run the games at decent frame rates because the new 5k cards do not support the tech and the games are falling back to CPU calculated PhysX and getting 30fps because of it.

Given implementation takes time, given that 9/10 versions implemented in the wile are FP32 flavor, and given NV made zero noise and gave no warning they were going to do this... There is a high chance the devs for both games have wasted months of time and resources on implementing a physics re-write only to have the API they chose deprecated out from under their feet.

Be prepared for a second physX push to update to FP64 calculations, or a full roll back to the older physics engine used.

[xSOSxHawkens]

Monk の投稿を引用：

The majority of Physx still runs on 50 series, only those running on 32 bit instead of 64 bit dont.

Thats the majority of PhysX titles with hardware acceleration support. Like 90% of them or more from most of what I have seen/read. The list of working titles with HW support on 5k is very short.

[ugafan]

I saw this on the blog post:

With the release of version 1.54, PhysX is now the default physics engine for all gameplay. Players who prefer the previous Bullet physics engine can switch back by using the "-bullet" command line argument in their Steam launch options.

[Wolfgang]

xSOSxHawkens の投稿を引用：

Unless these two games are updating to FP64 Physx then the devs are screwed.

NV just killed off 90% of PhysX support in their most recent release of the RTX5k cards.

People who play games that actually make heavy use of PhysX are having to put in second GPU's to run the games at decent frame rates because the new 5k cards do not support the tech and the games are falling back to CPU calculated PhysX and getting 30fps because of it.

Given implementation takes time, given that 9/10 versions implemented in the wile are FP32 flavor, and given NV made zero noise and gave no warning they were going to do this... There is a high chance the devs for both games have wasted months of time and resources on implementing a physics re-write only to have the API they chose deprecated out from under their feet.

Be prepared for a second physX push to update to FP64 calculations, or a full roll back to the older physics engine used.

Isn't that just the 32bit PhysX that Nvidia killed and not the 64bit PhysX? From all I heard on the official forums they are using 64bit PhysX.

[xSOSxHawkens]

Wolfgang の投稿を引用：

Okay, so running PhysX on the CPU isn't directly a really bad thing, right?

No, but yes.

CPU cannot calculate Physics as good as the GPU due to the type of load.

So if the game has a light number of calculations, then the CPU might handle it perfectly fine without any issue.

If the game has a decent number, the CPU might handle it to a playable level, but the GPU will do much better.

If the game has *allot* of physics calculations at one time, the CPU will not handle that well and the whole game engine will get bottlenecked on the physics calculations per frame to finish before the next frame can start so to speak. This will slow the whole frame rate down, and you might see sub-30FPS game play. This is where pushing the calculations onto the GPU *or* reducing their number are the only two options. This is where hardware PhysX comes into play, as it allows the calculations to be run on the GPU. This will come at a framerate cost still, but far less than running heavy loads on the CPU alone.

[Monk]

It's like 20 or 30 games from 15 years, ago using 32 bit affected by it.

[xSOSxHawkens]

Wolfgang の投稿を引用：

xSOSxHawkens の投稿を引用：

Unless these two games are updating to FP64 Physx then the devs are screwed.

NV just killed off 90% of PhysX support in their most recent release of the RTX5k cards.

People who play games that actually make heavy use of PhysX are having to put in second GPU's to run the games at decent frame rates because the new 5k cards do not support the tech and the games are falling back to CPU calculated PhysX and getting 30fps because of it.

Given implementation takes time, given that 9/10 versions implemented in the wile are FP32 flavor, and given NV made zero noise and gave no warning they were going to do this... There is a high chance the devs for both games have wasted months of time and resources on implementing a physics re-write only to have the API they chose deprecated out from under their feet.

Be prepared for a second physX push to update to FP64 calculations, or a full roll back to the older physics engine used.

Isn't that just the 32bit PhysX that Nvidia killed and not the 64bit PhysX? From all I heard on the official forums they are using 64bit PhysX.

Yeh, the 32bit/FP32 versions. If the devs plan to run 64 then they will be fine.

[Bad 💀 Motha]

Wolfgang の投稿を引用：

xSOSxHawkens の投稿を引用：

Unless these two games are updating to FP64 Physx then the devs are screwed.

NV just killed off 90% of PhysX support in their most recent release of the RTX5k cards.

People who play games that actually make heavy use of PhysX are having to put in second GPU's to run the games at decent frame rates because the new 5k cards do not support the tech and the games are falling back to CPU calculated PhysX and getting 30fps because of it.

Given implementation takes time, given that 9/10 versions implemented in the wile are FP32 flavor, and given NV made zero noise and gave no warning they were going to do this... There is a high chance the devs for both games have wasted months of time and resources on implementing a physics re-write only to have the API they chose deprecated out from under their feet.

Be prepared for a second physX push to update to FP64 calculations, or a full roll back to the older physics engine used.

Isn't that just the 32bit PhysX that Nvidia killed and not the 64bit PhysX? From all I heard on the official forums they are using 64bit PhysX.

That was the initial impression but it seems it's entirely removed from RTX 50 given that latest GPU-Z shows no PhysX features box on all RTX 50 series GPUs

[_I_]

https://www.pcgamingwiki.com/wiki/List_of_games_that_support_Nvidia_PhysX

a newer cpu can run physx the same as a dedicated nvidia gpu

its really no difference as long as the cpu has more cores/threads than the game can effectively use

as for the older 32bit titles, physx on a newer 64bit cpu is still more than fine