OT: Mix and match PCI-E cards in SLI?

[Defecario]

Someone asked me if it is possible to use different PCI-E cards in SLI.
I always see revies using identical cards, never different models or
different brands. Any idea if it would work or be unstable?

TIA

 

[DaveW]

The two cards must be IDENTICAL for SLI to work.