[SOLVED] Is it possible to connect RTX 3090 FE and RTX 2080 Super FE at the same time?

[alfred.x]

Hi Guys,

I have Asus ROG Zenith II Extreme Alpha Motherboard. Previously, I was using Nvidia RTX 2080 Super FE with that board. Now, I purchased RTX 3090 FE and removed RTX 2080 Super. Now, I would like to see is there any compatibility issue or the PC will crash if I plug both? If it is possible, definitely I will be using 3090 as my master. I am not looking to bridge both GPUs using NVLink, instead both GPUs may remain independent. But it will be useful to run some ML tools or if I can use the GPUs for different processes. I have a good 1500W PSU which can hold both GPUs.

Thank you.

 

[Lutfij]

What is the make and model of your PSU? How old is the PSU in your build? Please don't state it's in your sig, since sig space specs are subject to change over time, making this thread and any relevant suggestions/solutions moot to the same person in the boat that you're in now. We ask users to post their specs in the thread's body for posterity's sake.

As for your question, if your PSU can handle the combined power draw of the two cards and then some more, then you should be able to have both cards on your platform though imbalanced cards are more inefficient than having a dual GPU setup of the same make and model.

As for the driver's side of things, use DDU to rid all drivers from your platform, make sure you have both cards populating their respective slots and then install the latest Nvidia drivers.

 

[alfred.x]

Hi @Lutfij my PSU is Cooler Master MasterWatt Maker 1500 and is less than 6 months old.

Why I am planning for this setup is because my 2080 is sitting idle in it's box. I just wanted to use it if possible. Again, I am doubtful about drivers as you mentioned, I need to install drivers of both 2080 and 3090 right? And again, the display will work if connected to 3090 DP? Also may I ask you, what is mean by DDU?

 

[geofelt]

I think you are good.

It looks like you can physically install both.
Depending on where, one may operate at x16 and the other at x8.
4 x PCIe 4.0 x16 SafeSlots (supports x16, x8/x8, x16/x8/x8, x16/x8/x16/x8)

On power, I would imagine that your 1500w psu would have sufficient connectors and adequate power capability.

Windows now allows multiple drivers for graphics cards.
But, I suspect that the same driver will handle both RTX cards.

DDU is a driver uninstall utility. The main use would be to clean out amd drivers when converting to nvidia or vice versa.
It is probably not necessary.
Since you are now running with the 3090, you are good on that score.
Install the 2080 and see how it does.
If it seems to have a problem, install the latest driver and select a clean install.

 

[alfred.x]

Hi @geofelt thanks for your reply. Let me post the PCIe slot configuration diagram. Could you please tell me to which slot should I connect 2080 and 3090?

Thank you.

 

[Karadjgne]

Starting with Windows 10 was DX12. Unlike DX11 which supported SLI and Crossfire, DX12 was written primarily for MGPU, multiple gpu, which was designed to run 2x or more gpus independently yet simultaneously. Sli is a tik-toc, synchronous inputs, first one gpu then the other, so cards had to be identical chipsets. With mgpu you can run any card.

For most games there is little to no mgpu support as yet, high end gpus make that unnecessarily complex to code for no reason, but that's not true for production type work where one gpu can be dedicated to an encode and leave the other gpu untouched.

Personally, I'd just sell the 2080Super, it'll still bring a good price, because it's usefulness is limited and benefits even more limited for most usage.

 

[geofelt]

Hi @geofelt thanks for your reply. Let me post the PCIe slot configuration diagram. Could you please tell me to which slot should I connect 2080 and 3090?

Thank you.

That chart is on how to configure for sli.
It is not applicable to your intended use. Games no longer support sli.

All I can suggest is to put the 3090 in slot#1 which is where you probably have it now.

Then try the 2080 in one of the other slots, probably trying slot 3 first.
If you can't get it to do what you want, market the 2080 or keep it as a spare.