Sharing GPUs between machines.

[amelius]

So, I wanted to make a build where I have two machines, one that's a workstation, and another that's a more gaming machine, but I want to be able to swap the GPUs between them easily without moving them. 

 

I was thinking about using PCI riser cables, and then swapping those out for this, however, two issues:

1. I'd need to make it so that both power supplies could be used interchangeably, so I wouldn't need to plug the GPUs into a different power supply for each machine, (not sure how to make sure both PSUs play nice with each other)

2. Ideally, it'd be great to have some sort of "PCI Riser Switch" (whether a DIY thing or commercial, which could easily swap PCIe3.0x16 cards from routing to one motherboard to the other. 

 

The reason I'm doing this is because I have a powerful workstation which sometimes needs multiple GPUs for workloads, however, I also game, and when i do game, i find this machine reaches CPU bottlenecks because it's got a very high thread count processor, and I want to be able to move a GPU or a pair of GPUs over to another, lower cost more gaming oriented system easily without having to do much. Any thoughts on this? 

 

EDIT: Please stop suggesting that I do something else, and answer the actual question i'm trying to solve. No, buying more GPUs isn't the option I want, that's another $3000 roughly. No, my CPU really IS bottlenecking me, a TR2990WX does in fact game *worse* than a i78700k, but performs great for workstation tasks, like machine learning, which is what I use my workstation for primarily. 

[Crunchy Dragon]

What I would do is have a multi-GPU setup for your workstation tasks, and just disable that in your graphics control panel when you want to play games.

 

This eliminates the need for any extra hardware and over-complication.

 

EDIT: a high power CPU shouldn't be bottlenecking anything, are you sure you've got that worded correctly?

[amelius]

2 minutes ago, Crunchy Dragon said:

What I would do is have a multi-GPU setup for your workstation tasks, and just disable that in your graphics control panel when you want to play games.

 

This eliminates the need for any extra hardware and over-complication.

 

EDIT: a high power CPU shouldn't be bottlenecking anything, are you sure you've got that worded correctly?

I'm a 100% sure i'm wording that correctly. I know that I'm getting CPU bottlenecked because when I switch from a 1080 Ti to my Titan V for games, I get zero improvement, and I get under what fps people have gotten with "lower end" CPUs. What I mean is i have a Threadripper 2990WX which genuinely performs worse in games than say, a 8700k. You're misunderstanding the problem... it's not that there's too many GPUs on the machine... my setup is already virtualized, i can assign as many GPUs as i want... my problem is that the workstation CPU bottlenecks gaming applications, and I don't want to buy two more expensive GPUs, but I want to use them for both gaming and work stuff. I'm waiting on two 2080Ti's and a Titan V. I'd like to be able to use the 2080Ti's for gaming, but also for the workstation as needed, but i don't want to bottleneck them with a CPU that has insufficient single thread performance for games. I need the workstation for other stuff, but I want to take full advantage of my GPUs. 

[Streetguru]

9 minutes ago, amelius said:

 

Why 2 PCs? What budget/Country? Or do you already have some hardware?

Just buy another GPU...

 

AMD's workstation/server cards can be visualized across a bunch of PCs, but I don't know the specifics or costs
 

 

[amelius]

7 minutes ago, Streetguru said:

Why 2 PCs? What budget/Country? Or do you already have some hardware?

Just buy another GPU...

 

AMD's workstation/server cards can be visualized across a bunch of PCs, but I don't know the specifics or costs
 

 

Well, I already bought 2x2080Ti's for the workstation which currently has two 1080Ti's and a Titan V in it, and I don't want to buy another pair... I want to be able to use them fully as I need them in different cases... So far, nobody's actually tried to answer my question, and only has been suggesting doing something else. Believe me, if something else was a good solution, I've already considered it and ignored it for a reason... I'm asking how to solve this specific issue. I have a fully working workstation already, I want to add the second more gaming oriented machine that won't be CPU bottlenecked, and can fully utilize those GPUs for gaming when i do game, but when i'm working, i want those GPUs in the workstation machine. 

[Streetguru]

4 minutes ago, amelius said:

 

Just buy some cheap R3 2200G machine that will do gaming just fine and eventually add in some $200 GPU for 1080p gaming, wait if you have the money for all of those GPUs why not just build another gaming rig with an R5/i5 and 1070ti/1080 on the "cheap"?
 

You're asking for some crazy enterprise level solution that probably doesn't exist outside of hardware virtualization linked above, and that no one would really need.

[amelius]

Just now, Streetguru said:

Just buy some cheap R3 2200G machine that will do gaming just fine and eventually add in some $200 GPU for 1080p gaming
 

You're asking for some crazy enterprise level solution that probably doesn't exist outside of hardware virtualization linked above, and that no one would really need.

I'm asking for help figuring out a custom solution... Do you realize you're saying "buy a crappy machine for gaming when you have all this incredible hardware to use"? My current setup performs *well*, but it doesn't perform perfect... It's bottlenecked, but it'd still beat the hell out of a 2200G + $200 GPU... I have a 1440p 165Hz GSync display... the goal here isn't "i need a machine to game, i can't game" it's "i have hardware that for a specific case I can't take full advantage of, and I want to find a way to use it to it's full potential". I'm a 100% fine with a crazy solution... And I do in fact already use hardware virtualization, but that's not the solution here, because that doesn't really allow you to have the stuff on different machines without huge performance impacts, I virtualize and can assign any or all of my GPUs and CPU cores and RAM to specific virtual machines on the workstation, and currently I game in one of the VMs (before you ask, no, that's not the source of my performance hit, that's maybe a 1-2% difference). 

 

I'm asking a very simple set of questions:

1) Can I join two PSUs together so that they power both computers safely while playing nice. I know such options exist for powering a single computer with two PSUs, but i'm wondering if i can do that for two different PSU, so that they've got a shared ground and I can run GPUs off them and plug them into different machines without worrying. 

2) Are there *physical* switches that exist or could be made that would let me electrically switch from one PCIe3.0x16 riser cable to a second cable with the push of a button, so that i could "move" the GPU from one machine to another, not virtually, but physically. 

[Streetguru]

5 minutes ago, amelius said:

 

But it sounds like you have a ton of money, and all of the time/effort spent building a custom PCI-e switch or buying very expensive enterprise solutions...

 

could just be spent on another 1080ti for the gaming machine which would be like $600-700

https://www.microsemi.com/product-directory/ics/3724-pcie-switches
 

 

[amelius]

11 minutes ago, Streetguru said:

But it sounds like you have a ton of money, and all of the time/effort spent building a custom PCI-e switch or buying very expensive enterprise solutions...

 

could just be spent on another 1080ti for the gaming machine which would be like $600-700

https://www.microsemi.com/product-directory/ics/3724-pcie-switches
 

 

Again, I want to use the 2080Tis together with NVLink when I'm gaming, and when i'm not, move them back over to the workstation... If it was a 1080Ti sure, I'd go for it, but I want to use 2080Ti's to their maximum potential in both kinds of workloads... I don't understand why people refuse to actual help me solve the problem i came here with... I guarantee that the simplest solution, which is just having two daisy chained pci risers which i manually switch from one to another would cost less than getting another 2 2080Ti's... I'm just trying to do better than the simplest solution. 

[Streetguru]

1 minute ago, amelius said:

 

Unless you're attempting to power a 4k 120hz display why would you need 2 2080tis? Why not just move the 2 1080tis currently in the system to the gaming PC?

People can't help because you're looking for some crazy expensive enterprise solution as shown in that video.

[amelius]

16 minutes ago, Streetguru said:

 

 

This isn't quite what i'm looking for, looks like this is more about bifrucation, where I don't want that, I want a dumb switch that moves the electrical connection from one GPU to a different GPU. Basically, a PCI Riser version of a single pole double throw switch for PCIe x16 risers. 

[amelius]

1 minute ago, Streetguru said:

Unless you're attempting to power a 4k 120hz display why would you need 2 2080tis? Why not just move the 2 1080tis currently in the system to the gaming PC?

People can't help because you're looking for some crazy expensive enterprise solution as shown in that video.

a) see previous comment, the stuff in the video doesn't really address what i want... 

b) that's exactly what i'm trying to do, want to move to a 4k 120Hz display from my 1440p 165Hz display. 

[Streetguru]

1 minute ago, amelius said:

a) see previous comment, the stuff in the video doesn't really address what i want... 

b) that's exactly what i'm trying to do, want to move to a 4k 120Hz display from my 1440p 165Hz display. 

 

If you have a 3D printer, and are an electrical engineer or can hire an electrical engineer, you could try making a physical PCI-e switch between riser cables but I don't see it exactly working, otherwise wouldn't the product already exist?

You could just get 2 riser cables and put them next to each other, and move the GPUs whenever you wanted to switch systems I suppose

[Streetguru]

11 minutes ago, amelius said:

a) see previous comment, the stuff in the video doesn't really address what i want... 

b) that's exactly what i'm trying to do, want to move to a 4k 120Hz display from my 1440p 165Hz display. 

Like this yes?

[amelius]

9 hours ago, Streetguru said:

Like this yes?

Actually, yeah. Ideally, i'd like there to be some sort of easy way to switch them, without plugging/unplugging cables, but ultimately, the worst case scenario is literally just switching riser cables. 

[amelius]

9 hours ago, Streetguru said:

 

If you have a 3D printer, and are an electrical engineer or can hire an electrical engineer, you could try making a physical PCI-e switch between riser cables but I don't see it exactly working, otherwise wouldn't the product already exist?

I have all of the above, and I actually have background in EE, i was just hoping a product or combination of products existed to help, but as you pointed out before, this product almost certainly doesn't exist because there's no demand for it... there's very few scenarios, even in enterprise where this would ever be desired, I don't think that this is necessarily infeasible so much as it has very little if any demand.

[Streetguru]

Just now, amelius said:

I have all of the above, and I actually have background in EE, i was just hoping a product or combination of products existed to help, but as you pointed out before, this product almost certainly doesn't exist because there's no demand for it... there's very few scenarios, even in enterprise where this would ever be desired, I don't think that this is necessarily infeasible so much as it has very little if any demand.

I mean, it sounds like you could just afford 2 more 2080tis...

[amelius]

Just now, Streetguru said:

I mean, it sounds like you could just afford 2 more 2080tis...

Well, the first two going into my workstation i can write off taxes as a business expense since i use my machine for that... wouldn't be able to write off the second set since it'd be only in the personal rig... Trying to avoid that. 

[Streetguru]

12 minutes ago, amelius said:

Well, the first two going into my workstation i can write off taxes as a business expense since i use my machine for that... wouldn't be able to write off the second set since it'd be only in the personal rig... Trying to avoid that. 

You could just say all 4 are going into the workstation...