I have a sapphire 5850 on an ASUS P5E... I'm about to get a new P67 mobo and the 2500K i5 CPU, so im thinking about crossfire. Is it possible to crossfire with a different brand? ASUS POWERCOLOUR anything. Or should i sell it and get a 6870
You can crossfire different brands. I ran with two Gigabyte 5850s and one HIS 5850. One thing though... Just going by my own experience I'd recommend a single AMD card over multiple because the driver support for crossfire is just not there. You'll get great framerates, it's just the other issues you may not want to deal with. Just my opinion, based on my experience.
On the P67, you get 8x/16x/16x on a Maximus IV ($350) when you use three cards. Otherwise, it's 8x/8x with two on the Pro and above. Lower than the Pro motherboard, your looking at 16x/4x or 16x/1x depending on the board.
For PCIe bandwidth, 8x/8x is enough for 5850s. You really only need 16/16 for, say, GTX 580 or 6970 cards (or 590, 6990).
But anyway, all P55, P67, P68 boards only have 16 PCIe lanes to work with. The only way you get 16/16 on one of these boards is if they use the NF200 chip which works great, but it's only on the most expensive boards.
That's kind of why X58 is still a good choice. Sure the CPUs aren't as good as a 2600 but you get a better motherboard (32 PCIe lanes). Otherwise gotta wait till Ivy Bridge which should be the X58 equivalent Sandy Bridge