Windows 7: Crossfire over different GPUS

Hi, I have a HD 6870 gpu and a 7850 gpu, can I crossfire them ?

Hi xerox203 and welcome to Windows 7 Forums

Whilst both cards are capable of utilising crossfire, they cannot do so together. Both cards need to be from the same family series, i.e. 2x 6000 series or 2x 7000 series. Ideally, both cards should be identical. So that means, in your case, 2x 6870 or 2x 7950.

CrossfireX compatibility charts,

Looks like you might want to sell the 6870 and go with another 7950

I heard something like, you can xfire the cards but they took the specs of the lowest card ?, something like that ?

In this chart i can see 5800 series compatible with 6800 srs ? ain't 68 compatible with 78 ? :S

That would only be the HD 5750/5770 and the HD 6750/6770 as they are essentially the same card. There are a few updated features on the 6750/6770, but at the heart of each the are the same card. The same does not apply to any other cards from the 5xxx or 6xxx series, and definitely not with any from the 7xxx series.

That only applies within the same GPU/core family. For example from the chart the any of the 5830/5850/5870/5970 can all be used in Crossfire together because they all have the same core on them, they just have various parts of the core locked off for whatever reason; usually a defect that prevents it from being a 5870, but it perfectly fine as a 5850 or a 5830. The 5970 is essentially 2 5850's on a single PCB. That is where what you heard about them running at the specs of the lower card is from.

Lucid HydraLogix engine is also a way to get around these limitations. However it was only offered on one mother board if i recall...

As Solar mentioned your best for CF would be to sell the 6870 and grab another 7950.

You can use both the 6870 and 7950 at the same time for displays, but you just can't crossfire them.

And as Stormy mentioned they have to be from the same GPU/core family. As for the run at the 'slowest' card an example would be:

6870+6850 CF - the 6870 would run at 6850 Speeds.
7950+7970 CF - the 7970 would run at 7950 Speeds.

You can always OC the slowest card to get closer to the faster cards speed, but the CF will still be limited to the slowest cards speed.

At least CF has a bit more flexibility. With SLI, both cards have to be both the same family, but also the same model. (different brands are okay though)

Ie

GtX 670+GTX 680 = no SLI
GTX 670+GTX 670= SLI