I want to buy 7970 GPU. There are quite a few brands of it in my local store:
HIS, ASUS, GIGABYTE, Sapphire and XFX
I like Gigabyte and ASUS when it comes to motherboards or Nvidia videocards, but I never went to AMD yet. So I'm not sure about what brand dominates in AMD manufacturing. Is Gigabyte fine? WIll I be able to put a different brand of 7970 later in Crossfire?
You can mix and match different brands/models of HD7970's for crossfire, I'm pretty sure you could also crossfire a 7970 with a 7950 or 7990 when there released aswell.
Almost all HD7970's that are out at the moment are reference design ( I think XFX have a black edition HD7970) so most cards are the same just with a different sticker, buy the cheapest, but also have a look at the warranty periods for the different brands as they can vary.
What is the problem with reference cards? Still can OC them...
Reference design cards are almost always run hotter, and noisier than the after market - add in boards. Often reference designs cannot be overclocked as much as the likes of the ASUS DCU and GIGABYTE Windforce either.
At the moment you have 3 options for better cooling and more overclocking:
1. go with the XFX Black Edition which is a good card.
2. Wait for the GIGABYTE windforce, ASUS Direct CU, or MSI Twin Frozr
3. Buy a reference design and fit an after market cooler to it. WARNING: you will void your warranty.
Alternatively you can buy a reference design card and just accept that It'll be a bit more noisy and you shouldn't overclock it as much.