Will a third card work for PhysX?
Hi guys I have a MSI Z87 GD65 motherboard and 2x780's, if I purchased a third Nvidia card just for PhysX would this work when playing games in 3D?
Hi guys

I have a MSI Z87 GD65 motherboard and 2x780's, if I purchased a third Nvidia card just for PhysX would this work when playing games in 3D?

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#1
Posted 03/27/2014 05:17 AM   
Yep. I do it currently. You DO want to make sure that your motherboard officially supports 3xSLI though, just to guarantee that it'll run 3 cards without throttling the pci speed too low.
Yep. I do it currently. You DO want to make sure that your motherboard officially supports 3xSLI though, just to guarantee that it'll run 3 cards without throttling the pci speed too low.

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#2
Posted 03/27/2014 05:40 AM   
Thanks Volnaiskra, I will have to run 1x GTX780 in PCIe 1 and the other GTX780 in PCIe 3 slot (Is that how you have yours?) It has the following slots: • 3 x PCIe 3.0 x16 slots (support x16, x8/x8, x8/x4/x4 modes) • 4 x PCIe 2.0 x1 slots
Thanks Volnaiskra, I will have to run 1x GTX780 in PCIe 1 and the other GTX780 in PCIe 3 slot (Is that how you have yours?)

It has the following slots:

• 3 x PCIe 3.0 x16 slots (support x16, x8/x8, x8/x4/x4 modes)
• 4 x PCIe 2.0 x1 slots

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#3
Posted 03/27/2014 05:52 AM   
Just check the documentation of your motherboard to see what Pci speeds it does. Usually it's something like: 1 card: x16 2 cards: x8, x8 3 cards: x8, x4, x4 Going from x16 to x8 is fine (and is unavoidable on all but the most expensive mobos with anything over 1 card). But going down to 4x is a no-no, especially if it affects one or more of your SLI cards (SLI only officially supports 8x or higher)
Just check the documentation of your motherboard to see what Pci speeds it does. Usually it's something like:
1 card: x16
2 cards: x8, x8
3 cards: x8, x4, x4

Going from x16 to x8 is fine (and is unavoidable on all but the most expensive mobos with anything over 1 card). But going down to 4x is a no-no, especially if it affects one or more of your SLI cards (SLI only officially supports 8x or higher)

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#4
Posted 03/27/2014 06:08 AM   
[quote="Milamber*"]3 x PCIe 3.0 x16 slots (support x16, x8/x8, x8/x4/x4 modes)[/quote]Sorry, I didn't see this before. The 8x x4 x4 worries me. Officially, SLI requires 8x 8x or higher, but you'll be running in 8x 4x. I don't know for sure if it'll be a problem, but it might be. I was faced with the same dillema, and I ended up upgrading my motherboard just in case. I knew I wanted a PhysX card, because even my 2 Titans couldn't handle PhysX in Metro Last Light on their own without freezes (bloody PhysX - I love it, but the performance is ridiculous). But I didn't want to risk clipping my Titans' wings just for a PhysX card. Plus, upgrading my mobo gave me a chance to upgrade my CPU to Haswell. Anyway, If I remember correctly, I now have x8 x8 x8. If I were you, I'd try to get an old card (any old card from anywhere - borrow a friend's, or use an ancient one from your bottom drawer) and do some testing first. This is what I'd do: 1. Test SLI cards in a PhysX game (write down min, avg, max FPS.) 2. Test SLI cards in a NON-PhysX game [insert any old 3rd card and enable as a PhysX card] 3. Test all 3 cards in the PhysX game. 4. Test all 3 cards in the non-PhysX game. The comparison between #2 and #4 would interest me most. Because the cards doing the work would be identical (your SLI cards), but in #2 they would be working on x8 x8, but in #4 they would be working on x8 x4. If you don't see a significant drop in this comparison, then maybe you'll be ok.
Milamber* said:3 x PCIe 3.0 x16 slots (support x16, x8/x8, x8/x4/x4 modes)
Sorry, I didn't see this before. The 8x x4 x4 worries me. Officially, SLI requires 8x 8x or higher, but you'll be running in 8x 4x.

I don't know for sure if it'll be a problem, but it might be. I was faced with the same dillema, and I ended up upgrading my motherboard just in case. I knew I wanted a PhysX card, because even my 2 Titans couldn't handle PhysX in Metro Last Light on their own without freezes (bloody PhysX - I love it, but the performance is ridiculous). But I didn't want to risk clipping my Titans' wings just for a PhysX card. Plus, upgrading my mobo gave me a chance to upgrade my CPU to Haswell. Anyway, If I remember correctly, I now have x8 x8 x8.

If I were you, I'd try to get an old card (any old card from anywhere - borrow a friend's, or use an ancient one from your bottom drawer) and do some testing first. This is what I'd do:

1. Test SLI cards in a PhysX game (write down min, avg, max FPS.)
2. Test SLI cards in a NON-PhysX game

[insert any old 3rd card and enable as a PhysX card]

3. Test all 3 cards in the PhysX game.
4. Test all 3 cards in the non-PhysX game.


The comparison between #2 and #4 would interest me most. Because the cards doing the work would be identical (your SLI cards), but in #2 they would be working on x8 x8, but in #4 they would be working on x8 x4. If you don't see a significant drop in this comparison, then maybe you'll be ok.

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#5
Posted 03/27/2014 06:12 AM   
The board config gets into all sorts of craziness, because the Intel spec doesn't support anything more than 16 PCI lanes from the CPU. That means the usual setup is x8 x4 x4 for a 3 slot setup. In order to get more than that you end up having to get a board with an extra chip, the PLX chip. That allows for multiplexing the 16 lanes to do more, at the cost of some latency. General consensus seems to be that it's OK to have PLX chip. People don't tend to review or look at SLI or 3D Vision setups though, so it's hard to get a straight answer. @Milamber*: For your board, I think you'd be best served by doing x8 x8 for the video cards, and put the 3rd card in the PCIe 2.0 slot. If you are only running a single card in the 2.0 section, you'll get x8 on that slot, and that should be good for PhysX. I wouldn't run an asymmetric x8 x4 x4 setup with 3D Vision. Too many driver dependencies and expectations. Besides which, x8 PCIe 2.0 == x4 PCIe 3.0 If those are physical x1 slots, and thus no video card will fit, I'm not sure I'd go with a PhysX card. You could maybe try out the x8 x4 x4 combo and take it back if it didn't work.
The board config gets into all sorts of craziness, because the Intel spec doesn't support anything more than 16 PCI lanes from the CPU. That means the usual setup is x8 x4 x4 for a 3 slot setup. In order to get more than that you end up having to get a board with an extra chip, the PLX chip. That allows for multiplexing the 16 lanes to do more, at the cost of some latency.

General consensus seems to be that it's OK to have PLX chip. People don't tend to review or look at SLI or 3D Vision setups though, so it's hard to get a straight answer.


@Milamber*: For your board, I think you'd be best served by doing x8 x8 for the video cards, and put the 3rd card in the PCIe 2.0 slot. If you are only running a single card in the 2.0 section, you'll get x8 on that slot, and that should be good for PhysX.

I wouldn't run an asymmetric x8 x4 x4 setup with 3D Vision. Too many driver dependencies and expectations. Besides which, x8 PCIe 2.0 == x4 PCIe 3.0

If those are physical x1 slots, and thus no video card will fit, I'm not sure I'd go with a PhysX card. You could maybe try out the x8 x4 x4 combo and take it back if it didn't work.

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#6
Posted 03/27/2014 06:19 AM   
I'm sure someone is going to shut me down but there is seriously like 1-2 good physx game a year. I'd wait for the next 3d vision one you "want" before committing. Though if you do, play The Bureau = ) That game has awesome physx surprisingly. Crazy physx + sci fi setting = works
I'm sure someone is going to shut me down but there is seriously like 1-2 good physx game a year. I'd wait for the next 3d vision one you "want" before committing.

Though if you do, play The Bureau = )
That game has awesome physx surprisingly. Crazy physx + sci fi setting = works

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#7
Posted 03/27/2014 07:01 AM   
Thanks guys, appreciate the information. I think* I have 3x PCIe x16 slots? http://techreport.com/review/24945/msi-z87-gd65-gaming-motherboard-reviewed/5
Thanks guys, appreciate the information.

I think* I have 3x PCIe x16 slots?


http://techreport.com/review/24945/msi-z87-gd65-gaming-motherboard-reviewed/5

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#8
Posted 03/27/2014 07:02 AM   
Nope, standard config. You typically have to pay $300 or more for a board with x16 for multiple slots, the PLX chip is pricey. Your board won't run the third card at all it seems: [url]http://www.anandtech.com/show/6989/intel-z87-motherboard-review-with-haswell-gigabyte-msi-asrock-and-asus-at-200/6[/url] In there they mention that if you plug in a third card that SLI will be disabled because it requires x8 PCI lanes, either 2.0 or 3.0, but requires x8. You can't use the 2.0 slots because they are all physically x1 slots, which means no video card will fit, as they need x16 physical slots. (the physical number versus lane number is a really poor choice by Intel to describe these.) Your PCEi 3.0 slots are all x16 physical connectors, but the actual speed varies depending upon what is plugged in, all the way to x8 x4 x4.
Nope, standard config. You typically have to pay $300 or more for a board with x16 for multiple slots, the PLX chip is pricey.

Your board won't run the third card at all it seems:

http://www.anandtech.com/show/6989/intel-z87-motherboard-review-with-haswell-gigabyte-msi-asrock-and-asus-at-200/6

In there they mention that if you plug in a third card that SLI will be disabled because it requires x8 PCI lanes, either 2.0 or 3.0, but requires x8.

You can't use the 2.0 slots because they are all physically x1 slots, which means no video card will fit, as they need x16 physical slots. (the physical number versus lane number is a really poor choice by Intel to describe these.) Your PCEi 3.0 slots are all x16 physical connectors, but the actual speed varies depending upon what is plugged in, all the way to x8 x4 x4.

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#9
Posted 03/27/2014 09:14 AM   
[quote="eqzitara"]I'm sure someone is going to shut me down but there is seriously like 1-2 good physx game a year. I'd wait for the next 3d vision one you "want" before committing.[/quote]Yeah, you're not far off. Perhaps 3-4 if you want to be more generous. So I certainly don't want to shut you down. But in my experience, those games tend to have two things in common: (a) They're often excellent games (eg. Borderlands 2, Metro series, Batman Arkham series, Bioshock Infinite, Mirror's Edge, Shift 2) (b) They are often some of the most technically demanding games released, because devs who implement PhysX tend to implement all sorts of other goodies like Tesselation, SSAO, and so on (eg. Metro series, Arkham series, Cryostasis, Witcher 3) So, I'd argue that chances are good that a physX game will come along soon enough that you'll want to play (see #a), and chances are also good that your system will need all the help it can get when you do (see #b). Though it's mainly used in FPS or action games for some reason. If you mainly play strategy, RPG or racers, then it's probably not worth it (with the probable exception of Witcher 3, which will likely be both awesome and system-demolishing). [quote="Milamber*"]Thanks guys, appreciate the information. I think* I have 3x PCIe x16 slots? http://techreport.com/review/24945/msi-z87-gd65-gaming-motherboard-reviewed/5 [/quote]Yes, but if you put more than one GPU card into them, they become 8x or x4 slots (2 cards = x8 x8; 3 cards = x8 x4 x4) What you really want is x8 x8 x8, which surprisingly few motherboards provide, at least at a reasonable price point. A PhysX card for a single-GPU user is a piece of cake. Sadly, for SLI users it's more complicated.
eqzitara said:I'm sure someone is going to shut me down but there is seriously like 1-2 good physx game a year. I'd wait for the next 3d vision one you "want" before committing.
Yeah, you're not far off. Perhaps 3-4 if you want to be more generous. So I certainly don't want to shut you down. But in my experience, those games tend to have two things in common:

(a) They're often excellent games (eg. Borderlands 2, Metro series, Batman Arkham series, Bioshock Infinite, Mirror's Edge, Shift 2)

(b) They are often some of the most technically demanding games released, because devs who implement PhysX tend to implement all sorts of other goodies like Tesselation, SSAO, and so on (eg. Metro series, Arkham series, Cryostasis, Witcher 3)


So, I'd argue that chances are good that a physX game will come along soon enough that you'll want to play (see #a), and chances are also good that your system will need all the help it can get when you do (see #b).


Though it's mainly used in FPS or action games for some reason. If you mainly play strategy, RPG or racers, then it's probably not worth it (with the probable exception of Witcher 3, which will likely be both awesome and system-demolishing).

Milamber* said:Thanks guys, appreciate the information.

I think* I have 3x PCIe x16 slots?

http://techreport.com/review/24945/msi-z87-gd65-gaming-motherboard-reviewed/5

Yes, but if you put more than one GPU card into them, they become 8x or x4 slots (2 cards = x8 x8; 3 cards = x8 x4 x4)

What you really want is x8 x8 x8, which surprisingly few motherboards provide, at least at a reasonable price point.

A PhysX card for a single-GPU user is a piece of cake. Sadly, for SLI users it's more complicated.

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#10
Posted 03/27/2014 09:25 AM   
Ummm, forgive me if this has already been addressed - I didn't read everyone's response in detail. Granted, I'm no expert, but are you certain you will see any benefit running a PhysX dedicated card when you are already running two beefy 780's? Seriously, a year ago I tried running a GTX 450 I had laying around for PhysX alongside my 690, and the 450 actually slowed things down. When you have a good card like a 690 or 780, or TWO 780's, they seem to be quite capable on their own.. Just my two cents.
Ummm, forgive me if this has already been addressed - I didn't read everyone's response in detail. Granted, I'm no expert, but are you certain you will see any benefit running a PhysX dedicated card when you are already running two beefy 780's?

Seriously, a year ago I tried running a GTX 450 I had laying around for PhysX alongside my 690, and the 450 actually slowed things down. When you have a good card like a 690 or 780, or TWO 780's, they seem to be quite capable on their own.. Just my two cents.

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#11
Posted 03/27/2014 08:58 PM   
[quote="SnickerSnack"]Ummm, forgive me if this has already been addressed - I didn't read everyone's response in detail. Granted, I'm no expert, but are you certain you will see any benefit running a PhysX dedicated card when you are already running two beefy 780's? Seriously, a year ago I tried running a GTX 450 I had laying around for PhysX alongside my 690, and the 450 actually slowed things down. When you have a good card like a 690 or 780, or TWO 780's, they seem to be quite capable on their own.. Just my two cents. [/quote]Yup, it makes a huge difference. See Volnaiskra's blog post about it with data. Pretty compelling. [url]http://volnapc.com/how-much-difference-does-a-dedicated-physx-card-make[/url] Looking at your motherboard, I would expect that the 690 with a 450 to work OK. If you plugged it into the closest slot, that would drop your x16 main slot to x8, but give x8 for the 450. If you plugged it into the far slot, that would keep your x16 for the main dual-gpu, and give x4 for the 450. Not sure, lots of details missing. Also, not all games are improved. It's now pretty clear to me that the motherboard can cause some serious problems here with a PhysX card. I didn't see this before, but these discussions with Volnaiskra's existence proof led me to research some more. If you have a motherboard that does not implement a PLX chip, it's not worth doing. You absolutely need that extra bandwidth of x8 x8 x8 setup, or at least not botch the SLI itself while adding a third card. The CPU itself only provides 16 lanes of PCIe, divided how the motherboard maker likes. x8 x8 is OK, but then the third card for PhysX is stuffed off in no-mans land off the Southbridge chip. That means it's effectively geting x2, no matter what they say. The bottleneck between CPU and Southbridge is what killed my experiment I think. Anyway, mumbo-jumbo. If you want this to work, you absolutely need a higher-end motherboard that includes PLX, and you cannot get away with a sub-$300 board. Because my experiment was flawed by the P55 chipset, I think the jury might still be out using a 'crap-card' from your drawer for this. If you have a good motherboard, the card itself may not matter as much.
SnickerSnack said:Ummm, forgive me if this has already been addressed - I didn't read everyone's response in detail. Granted, I'm no expert, but are you certain you will see any benefit running a PhysX dedicated card when you are already running two beefy 780's?

Seriously, a year ago I tried running a GTX 450 I had laying around for PhysX alongside my 690, and the 450 actually slowed things down. When you have a good card like a 690 or 780, or TWO 780's, they seem to be quite capable on their own.. Just my two cents.
Yup, it makes a huge difference. See Volnaiskra's blog post about it with data. Pretty compelling.

http://volnapc.com/how-much-difference-does-a-dedicated-physx-card-make


Looking at your motherboard, I would expect that the 690 with a 450 to work OK. If you plugged it into the closest slot, that would drop your x16 main slot to x8, but give x8 for the 450. If you plugged it into the far slot, that would keep your x16 for the main dual-gpu, and give x4 for the 450.

Not sure, lots of details missing. Also, not all games are improved.


It's now pretty clear to me that the motherboard can cause some serious problems here with a PhysX card. I didn't see this before, but these discussions with Volnaiskra's existence proof led me to research some more.

If you have a motherboard that does not implement a PLX chip, it's not worth doing. You absolutely need that extra bandwidth of x8 x8 x8 setup, or at least not botch the SLI itself while adding a third card. The CPU itself only provides 16 lanes of PCIe, divided how the motherboard maker likes.

x8 x8 is OK, but then the third card for PhysX is stuffed off in no-mans land off the Southbridge chip. That means it's effectively geting x2, no matter what they say. The bottleneck between CPU and Southbridge is what killed my experiment I think.


Anyway, mumbo-jumbo. If you want this to work, you absolutely need a higher-end motherboard that includes PLX, and you cannot get away with a sub-$300 board.

Because my experiment was flawed by the P55 chipset, I think the jury might still be out using a 'crap-card' from your drawer for this. If you have a good motherboard, the card itself may not matter as much.

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#12
Posted 03/27/2014 09:34 PM   
Good read, thanks for the info bo3b and Volnaiskra :) You just saved me $150 AUD!
Good read, thanks for the info bo3b and Volnaiskra :)

You just saved me $150 AUD!

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#13
Posted 03/27/2014 09:56 PM   
Thanks for sharing that, bo3b. I didn't know that about the Southbridge. It makes me glad I shelled out the money for a PLX-chip motherboard. I didn't know for sure at the time if it was overkill or necessary. Though it sounds like it was pretty necessary, even though pretty much the only options were basically the top-tier mobo from each company!* I just wish they made motherboards with larger gaps between the PCI slots. Having two hot VGA cards next to each other really cranks up the heat. I'd love to be able to have two SLI cards and a full size PhysX card without them all choking each other. In fact, even with just normal 2x SLI with both cards adjacent, my upper card was regularly 10 degrees warmer than the lower card. *By the way, while I'm on the subject of mobos: please everyone stay away from Asrock. It's my second Asrock in a row, and I hate them. The main stuff (ie CPU, SLI, PhysX) works fine, but I've had no end of little problems with booting, bad USB slots etc. I actually had to sell an SSD because my board was *incapable* of telling apart two different SSDs that happened to both be the same brand and model (bought years apart and ofc different serial numbers). It kept trying to boot off the wrong one, and there was absolutely no way to tell it which one was which. The Asrock tech support guy basically just shrugged his shoulders when I told him.
Thanks for sharing that, bo3b. I didn't know that about the Southbridge.

It makes me glad I shelled out the money for a PLX-chip motherboard. I didn't know for sure at the time if it was overkill or necessary. Though it sounds like it was pretty necessary, even though pretty much the only options were basically the top-tier mobo from each company!*

I just wish they made motherboards with larger gaps between the PCI slots. Having two hot VGA cards next to each other really cranks up the heat. I'd love to be able to have two SLI cards and a full size PhysX card without them all choking each other. In fact, even with just normal 2x SLI with both cards adjacent, my upper card was regularly 10 degrees warmer than the lower card.




*By the way, while I'm on the subject of mobos: please everyone stay away from Asrock. It's my second Asrock in a row, and I hate them. The main stuff (ie CPU, SLI, PhysX) works fine, but I've had no end of little problems with booting, bad USB slots etc.

I actually had to sell an SSD because my board was *incapable* of telling apart two different SSDs that happened to both be the same brand and model (bought years apart and ofc different serial numbers). It kept trying to boot off the wrong one, and there was absolutely no way to tell it which one was which. The Asrock tech support guy basically just shrugged his shoulders when I told him.

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#14
Posted 03/28/2014 01:49 AM   
Since that experiment, I've upgraded to Maximum Hero board, which does x8 x8 x4 in SLI, where the x4 is off the SouthBridge. Since then, Intel updated the DMI interface to run a lot faster, and it may not bottleneck anymore. This is sort of like Milamber's setup, although this is Z87 chipset. I'll give it another try with my third slot and report back when I get a chance.
Since that experiment, I've upgraded to Maximum Hero board, which does x8 x8 x4 in SLI, where the x4 is off the SouthBridge. Since then, Intel updated the DMI interface to run a lot faster, and it may not bottleneck anymore. This is sort of like Milamber's setup, although this is Z87 chipset.

I'll give it another try with my third slot and report back when I get a chance.

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#15
Posted 03/28/2014 02:05 AM   
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