Multiple GPU's

[Taynak]

So I have always been under the assumption that if you want to run more than one graphics card in your system that you need to have them all be exactly the same... manufacturer, chip, build, everything... 

 

Is this true or am i just missing something?

[3 Lions]

It has to be the same GPU core (chip) for Nvidia anyway. 

[Taynak]

Just now, LinusTechTipsFanFromDarlo said:

It has to be the same GPU core (chip) for Nvidia anyway. 

ok... what about AMD then?

[3 Lions]

Just now, Taynak said:

ok... what about AMD then?

Not sure on AMD GPU's. 

[Mick Naughty]

You can run any cards combo you want. Don't need to be a specific anything.

[Zando_]

6 minutes ago, Mick Naughty said:

You can run any cards combo you want. Don't need to be a specific anything.

^^^ You could put 4 different cards in a PC, assuming you have 4 properly spaced PCIe slots. You only need the same model if you're trying to SLI or Crossfire them. (IIRC you can crossfire something like an RX480 and 580 though, or 580 and 570, but can't jump generations of cards). 

[-rascal-]

1 hour ago, Taynak said:

ok... what about AMD then?

 

1 hour ago, LinusTechTipsFanFromDarlo said:

Not sure on AMD GPU's. 

 

With nVidia SLI:

• Must be the same GPU (e.g. GTX 1080 + GTX 1080)
• Must have the same amount of VRAM (can't do SLI with GTX 1060 6GB + GTX 1060 3GB ...can't do SLI with 1060's but let's pretend)
• May sometimes be picky with the vBIOS is different
• Can be different GPU and Memory frequencies
• Can be different brands (e.g. EVGA RTX 2080 + MSi RTX 2080)

AMD Crossfire:

• Can be different GPU, but as long as it is the same GPU core/architecture (e.g. Crossfire R9-390X + R9-390 ... Radeon HD  7970 + R9-280X)
• Can be different VRAM (e.g. RX-580 4GB + RX-580 8GB)
• Can be different GPU and Memory frequencies
• Can be different brands

 

IDEALLY, for the most optimal performance, you would want the GPUs to be identical -- or nearly identical -- in both nVidia SLI and AMD Crossfire.

 

 

EDIT:

From nVidia's SLI FAQ:

Quote

https://forums.geforce.com/default/topic/469402/sli/faq-quot-will-these-two-cards-work-in-sli-quot-sli-what-works-with-what-/

- All graphics cards must have the same GPU
(This means the model name for the GPU. An EVGA GTX480 FTW Edition is simply a GTX480 in terms of SLI.)
-- You can only use SLI with two, three or four or more Identical GPUs.

There are exceptions to this rule, but only with very old hardware so I have omitted them. 
Note: Be careful with the extensions on GPUs. An extension denotes a totally different GPU. For example the GTX460SE, GTX560Ti and GTX Titan are not SLI capable with the GTX460, GTX560 and GTX Titan Black respectively. If you are unsure what extensions exist, check Geforce.com


- All GPUs must have the same amount of VRAM and an identical Bus Width
-- You cannot use a "2GB" version with a "4GB" version or "3GB" version with a "6GB" version in SLI or a 1GB 192 bit bus with a 1GB 256 bit bus Etc.
Note: It used to be possible to enable SLI on cards with differing VRAM but this is no longer available.
   
Note: In SLI the amount of usable VRAM does not stack. It works like a RAID1 hard disk array where data is mirrored between each GPU. For example, having 3 GPUs with 4GB VRAM means you will only have 4GB available, not 12GB.

- Manufacturer
-- You can mix and match any manufacturer of nvidia GPUs. EVGA works fine with Asus etc.

- Clock speeds 
-- You are able to use different clock speeds on each GPU working in SLI. An "overclocked" card will work with a "plain" card just fine.