AMD Crossfire compatibility

[Roycewicz]

All right! So AMD's older cards like the HD4870 for example could have been crossfired with any other HD48** cards. But the official AMD website that is supposed to show me the compatibility has not been updated since R9 200 series.
What's the current situation in this topic? RX480+RX470 possible? or R9 390+RX480? or it's simply no longer true that you can crossfire different cards?

[MrPants_]

Pretty sure you can crossfire RX480 + RX470, but don't quote me on that. I don't think you can crossfire an R9 390 and an RX480, as they're different gpu architectures. I might be wrong though. 

[MidnightBanshi]

I think you would get more horsepower out of doing 2 RX 480s in CrossfireX than doing two different engines in your rig.

[Roycewicz]

It's just a theoretical question,

1 minute ago, MidnightBanshi said:

I think you would get more horsepower out of doing 2 RX 480s in CrossfireX than doing two different engines in your rig.

no questions there

[TheRandomness]

5 minutes ago, Roycewicz said:

It's just a theoretical question,

no questions there

You can crossfire any two cards that use the same chip. 470 and 480 work because they're both Ellesmere chips, but the 480 would 'downgrade' itself to a 470 when doing so.