AMD Crossfire not working.

[colinwilloughby]

I have fitted a second AMD XFX 2gb HD 5970 GPU. Device manager recognises the two cards. AMD Catalyst set to crossfire (Clean driver download). When running my flight sim, the frame rate does not improve. If I disable crossfire, the frame rate stays the same (so the second card is not working but individually both cards work OK). Also there is no output from the second card ports(When in crossfire should both card ports work?). I have tested the system with a second 1200W PSU with same results, Also I have looked on other forums and not found any help (including AMD help desk) Can any one suggest anything??

 

[Mellon Head]

Not all games support Crossfire. Are you sure that the flight sim supports Crossfire?

Also, IIRC, the second card's ports don't work when the card is in Crossfire mode. It's been a while though, I could be wrong.

 

[colinwilloughby]

Thanks for the reply MH. I have not considered Microsoft flight sim not being crossfire capable. I will check this out and come back with any info. I have read my motherboard's manual which states that when installing, Priority is to be given to one of the cards slot's which (I believe) will mean that the second card serves to assist the designated main card so the ports on the second card would not be expected to function.

 

[GokAy]

Some searching shows that FS does not support either SLI (Nvidia) or Crossfire (AMD). You can check your setup in some benchmarks like:

- Unigine Valley https://unigine.com/products/benchmarks/
- 3D Mark 3DMark cross-platform benchmark for Windows, Android and iOS - scroll down for free version, Basic Ed.

Run benchmark twice, with 1 card and 2 cards.

Unfortunately, not all games are SLI/Crossfire enabled. It depends on the developer.

 

[Mellon Head]

I have read my motherboard's manual which states that when installing, Priority is to be given to one of the cards slot's which (I believe) will mean that the second card serves to assist the designated main card so the ports on the second card would not be expected to function.

That is also my understanding of how Crossfire works. Only the ports on one card do the work, the other GPU just assists.