I have a AMD A8-3870K APU that has AMD's DualGraphics feature. This means that you can run in 'CrossFire' with another GPU. My question: Will this feature also work with a Radeon HD 6000 series GPU from a different brand? For excample, I saw a Asus HD6670-2GD3 graphics card which is a Radeon HD 6670 card. Will this one work with this feature?
Any HD6670 will work with the feature, so you are good if you grab that card.
AMD doesn't make any in house cards except for their FirePro's. Of course you have to buy another brand, it's the same card essentialy.
Exactly what Pip/Double said, AMD does not make any of their cards in house, unlike Nvidia. Any 6670 That you get should work (Asus, XFX, you name it.)
Oh I see, I thought they did a few because they are displayed on the box of my APU