HD4870 X2 - CrossFire doubt

[Hirager]

I am preparing to buy a new GPU. Currenlty I am most inclined to buy a used HD4870 X2. However, on one of auction descriptions I found that on this card two GPUs are "crossfired" together. How does it relate to r600 driver, which has no support of CrossFire? Is the card seen by OS as a single or two GPUs? My understanding is, if OS is booted with two GPUs, it utilizes only one of them.

[agd5f]

X2 cards show up as two GPUs on the PCI bus. Currently the open source driver is not able to utilize both chips in a crossfire configuration, but it will load on both GPUs and in theory you can use them independently, however, only one GPU has displays wired to it.

[Hirager]

I see. So I have to scratch all double cards. Thanks. Now the most appeling one is the HD 4890.

[agd5f]

They should still work with the open source driver, however you can only take advantage of one GPU at the moment.

[Hirager]

Considering I will not have any opportunity to benefit from two separate GPUs, like 3D modelling, I am better off with a cheaper, single card. I also considered HD 5870, but those are too expensive yet. And I am not going to buy anything else then the most powerful card of a generation. Now I am aiming for a cheap, but powerful one (it has twice as much flops as my current one, and much better driver support), and then I will be able to save up for the next generation card.