Crossfiring 6950's

[chaosrapture]

hey guys.

I have a few questions about crossfiring two ATI HIS 6950 IceQ X's.

I'm building a new rig and i'm placing my current 6950 IceQ turbo in my new rig along with another 6950 however I just realised that the second card I bought to place alongside my current 6950 isn't the turbo version. Will this present a problem as the two cards have different clock speeds?

The second question I have is how exactly do I crossfire the cards. I did SLI two nvidia cards a long time ago using the ribbon across the cards but is this still how you crossfire?.

cheers guys

 

[Chainzsaw]

Hello,

You should be able CF them no problem. I believe the CF will just downclock to the slowest GPU. However - i think you can just use overdrive to match the speed of the "higher speed" 6950.

Also CF requires a "bridge" as well. Quite similar to SLI bridge actually.

 

[willard]

You might have issues with the differing clock speeds. Luckily, it's easy to adjust them to make them match using tools like MSI Afterburner (my favorite AMD overclocking util).

And yes, you crossfire them with a crossfire bridge, which is a little strip that connects the two cards.

 

[chaosrapture]

cheers for the info guys.

i think its only 40mhz between the two cards so afterburner should be sufficient.

I do have my current 6950 running at 900mhz core and 1400mhz memory however.

Will i see a good increase on this with standard clocked (840mhz) 6950's?

 

[willard]

I think the 6950 reference design is 800 MHz, so your new one is also factory overclocked. As far as the performance boost, yes, it will be very dramatic.

I'd recommend overclocking the new card as high as it will go, then downclocking the old one to match (or if you're lucky, overclock it). That will get you the best possible speed out of them.