Do PCIe switch/split exist?

[Lucas Zanella]

I need to use 2 different GPUs on my VMs, but not on the same time because I don't have the power needed. I'd like to be able to switch from one to another or even split them (the 2 are recognized at the same time) but only power one per time.

 

A split I imagine as being something that makes 2 available at the same time

 

A switch I imagine as being something that I mechanically change to one or another, just like an HDMI switch for TVs

 

It'd be nice to not need to restart the computer but if it's needed also it's no problem.

 

Do such thngs exist?

[Helpful Tech Witch]

nope, but better psus exist

 

[Lucas Zanella]

1 minute ago, HelpfulTechWizard said:

nope, but better psus exist

 

the only problem I'm trying to fix is having ot manually change from one GPU to another

[Helpful Tech Witch]

Just now, Lucas Zanella said:

the only problem I'm trying to fix is having ot manually change from one GPU to another

the switch doesnt really exist, and splitters require both gpus to be powered. you just need a stronger psu.

[rcmaehl]

4 minutes ago, Caroline said:

yeah... that's not how graphics cards work, cut the power to one and the system will hang or restart. Get a better PSU

Actually, PCIe is designed to be hotswappable. I'm sure something can be done in Linux, but I'm unsure in Windows. Motherboard compatibility will vary

[Helpful Tech Witch]

3 minutes ago, rcmaehl said:

Actually, PCIe is designed to be hotswappable. I'm sure something can be done in Linux, but I'm unsure in Windows. Motherboard compatibility will vary

yeah, there was that disastorus ltt video about pcie hotswap.

[jaslion]

Doesn't exist get a better psu. Sure pcie is hotswap but doing that for a gpu is a one way street to crashtown.

[rcmaehl]

5 minutes ago, HelpfulTechWizard said:

yeah, there was that disastorus ltt video about pcie hotswap.

Only for the first 16 minutes
 

 

[rcmaehl]

2 minutes ago, Caroline said:

In any case, this is how an hypotetical switch would work, a 6 prong rocker switch breaks or closes the circuit for a single card.

It's quite simple, but will it work software-wise? I have no idea.

 

To be fair graphics cards should be drawing power from both the PCIe slot and the 6 pin cables. It MIGHT work if there's no load, along other setup requirements.

[Jurrunio]

Is the build still this?

Quote

PSU: Corsair CX550 CX (https://www.mercadolivre.com.br/p/MLB8753974?pdp_filters=item_id:MLB1423141312#cart_referer=item)
Motherboard: Gigabyte B450m Ds3h Amd Am4 Ddr4 Ryzen B450  (https://produto.mercadolivre.com.br/MLB-1118727461-placa-me-gigabyte-b450m-ds3h-amd-am4-ddr4-ryzen-b450-_JM?variation=32295126896&quantity=1)
SSD: Ssd Kingston 500gb A2000 M.2 2280 Nvme Pcie 3.0 (https://produto.mercadolivre.com.br/MLB-1331169458-ssd-kingston-500gb-a2000-m2-2280-nvme-pcie-30-novo-c-nf-_JM?quantity=1)
CPU: Am4 Amd Ryzen 7 2700x 4.35ghz Cooler W. Prism (https://produto.mercadolivre.com.br/MLB-1430621528-processador-am4-amd-ryzen-7-2700x-435ghz-cooler-w-prism-_JM)
RAM: 8x of 8 GB 1x8GB Kingston HX424C15FB2/8 (https://www.mercadolivre.com.br/p/MLB14728564?pdp_filters=item_id:MLB1427185158#cart_referer=item)
GPU 1: PcYes GeForce 700 Series PY730GT12801G5 1GB (https://www.mercadolivre.com.br/p/MLB14954256?pdp_filters=item_id:MLB1396781950#cart_referer=item)
GPU 2: Galax GeForce GTX 16 Series 60SRH7DSY91C 6GB (https://www.mercadolivre.com.br/p/MLB14947754?pdp_filters=item_id:MLB1406258510#cart_referer=item)
WIFI: Pci Express Wireless Dual Band Ac1300 Archer T6e  (https://produto.mercadolivre.com.br/MLB-1077813257-adaptador-pci-express-wireless-dual-band-ac1300-archer-t6e-_JM?quantity=1)

 

[Lucas Zanella]

3 hours ago, Jurrunio said:

Is the build still this?

 

yes but with different motherboard

[Jurrunio]

1 hour ago, Lucas Zanella said:

yes but with different motherboard

then I dont see why a 1660 and GT710 will overload a 550w PSU with the rest of the stuff, gT710 is limited to only 20w.

[Lucas Zanella]

2 minutes ago, Jurrunio said:

then I dont see why a 1660 and GT710 will overload a 550w PSU with the rest of the stuff, gT710 is limited to only 20w.

Im not using with the GT750, Im using GTX 1660 and RX 560

[Kisai]

6 hours ago, Lucas Zanella said:

I need to use 2 different GPUs on my VMs, but not on the same time because I don't have the power needed. I'd like to be able to switch from one to another or even split them (the 2 are recognized at the same time) but only power one per time.

 

A split I imagine as being something that makes 2 available at the same time

 

A switch I imagine as being something that I mechanically change to one or another, just like an HDMI switch for TVs

 

It'd be nice to not need to restart the computer but if it's needed also it's no problem.

 

Do such thngs exist?

Technically... you can hotplug PCIe. Practically, nope, don't do it. You're very likely to kill something, and this is why you won't find the kind of thing you're asking for. Mechanical switches don't hit all the pins at the same time, and anyone who has used a parallel port switch back in the 90's will tell you how god-awful mechanical switching is.

 

You have two options here. Plug both GPU's in if you have the PCIe slots and then idle the one not in use, or only use one GPU and never use both VM's. If the PSU is not sufficient, then that is the thing you need to fix, and is a better, safer, investment than trying any kind of electrical-mechanical switch.

 

Failing that, buy the needed parts to put the GPU in an eGPU chassis and connect it via TB3. I don't recommend this strategy, even though it solves the PSU power problem, it often comes at the cost of permanently occupying the 4 PCIe lanes in the system if you have to add an expansion card for TB3. So if you have 16 lanes for your GPU normally, and 8x/8x with both GPU's in the system, you get 8x/4x if you put one on the TB bus instead, leaving 4 lanes unable to be used.

 

Anyway. As far as hotplugging goes, you certainly don't want to hotplug PCIe power. That will likely make the system instantly shutdown.

[terminalinfinity]

9 hours ago, HelpfulTechWizard said:

yeah, there was that disastorus ltt video about pcie hotswap.

Yup and Linus only got it working because he can talk to ASUS engineers and developers directly who walked him through it

 

Also IIRC, he also got a developer BIOS that isn't publicly available.