7970 Crossfire Pairing

[deFiniLoGy]

Do anyone here usually pair up display cards from different brands for crossfire?

I myself own a Sapphire HD7970 Vapor-X 3GB running at 1050/1500, and happen to pick up a second hand MSI HD7970 Lightning Boost 1150/1500 from my friend.

A few questions:

1. which card is more quiet in idle? (So that I should connect that as my primary card)
2. Do I have to OC the card (i.e. Vapor-X) to match the clock of the MSI one or is there not a big difference?
3. Will Vapor-X bottleneck the MSI or should I get another MSI card.

 

[ArchAndroid]

The brands do not have to be identical, the most important thing is that the chip is from the same family, the 7900 series.

1. This depends on the layout of your case and cooling; the best way to find is simply by trial and error.

2. No you don't have to OC the Sapphire card to match the MSi one but CrossFire will revert to the highest common speed between both cards which would be 1050MHz.

3. No

 

[old gamer]

whilst you can mix brands and models ie 7970 + 7950 i would stick to identical cards,
ive had about five crossfire setups and from my experience when ive use 2 identical gpu's it has been less problematic. could be pure luck but thats the way i think about crossfire

 

[tommybhoy]

2. No you don't have to OC the Sapphire card to match the MSi one but CrossFire will revert to the highest common speed between both cards which would be 1050MHz.

No it won't, CrossFire runs on independent clocks, it's up to the individual game/BM to utilise X amount on each core regardless the clocks, but most of the time, the higher clocked card utilises less of the core.

If you have/thinking about a 120Hz monitor or 120Hz 3D, the Lightning would have to be the lower/2nd gpu as it doesn't have any DL-DVi connections.

As long as both gpu's have fully unlocked voltage control, AB will oc both cards.

 

[bemaniac]

I use 2 mismatched cards. One on a ghz bios and one on its own gigabyte 1000mhz bios with no boost option. I just set them to 1100mhz in AB and sit back and play.