Question about Crossfire

[Lee Pigdon]

So i was wondering do both GPUs need to be identical for it to work?

[Skyfrog]

From what I understand they have to be the same GPU family and have the same amount of RAM, same bus width, etc. The manufacturer can be different.

 

Correction, it looks like you actually can use different RAM amounts as pointed out below. :)

[Billus]

Has to be from the same family if that makes sense. So 7970 with a 7950 and/or 290 or 280. Similarly a 7770 and a 7750 can be paired. However, the higher end card will run only as fast as the second GPU. GPU memory is only as high as the lowest card. So 1GB + 2GB still is 1GB. Same as 2GB and 2GB is still 2GB. Hope this helps.

[spikey_richie]

http://en.wikipedia.org/wiki/AMD_CrossFireX

 

"CrossFire can be implemented with varying-GPU cards of the same generation (this is in contrast to Nvidia's SLI, which generally only works if all cards have the same GPU). This allows buyers who have varying budgets over time to purchase different cards and still get the benefits of increased performance. With the latest generation cards, they will only crossfire with other cards in their sub series. For example, GPU in the same series can be crossfired with each other. So a 5800 series GPU (e.g. a 5830) can run together with another 5800 series GPU (e.g. 5870). However GPUs not in the same hundred series cannot be crossfired successfully (e.g. a 5770 cannot run with a 5870)."