Sapphire's HD 7950 Vapor-X comes with a large dual-fan cooler that uses the company's famous vapor-chamber technology. On the Vapor-X you will also find a "Lethal Boost" button which switches to a second BIOS with higher clock speeds. With this BIOS, clocks are increased to 950 MHz GPU and 1250 MHz memory.The Gigabyte is good as well.
I love my Sapphire 7950. It's been one of the best video cards I've owned and have used in any build that I've done. I've used back Radeon 9800 Pro, 2900 XT(Sapphire), 4850(Sapphire), GTX 560Ti, GTX 570, 7770(Sapphire), and 7950(Sapphire).
I know it seems like i'm set on Sapphire, which I am, but why switch when I've had nothing but success with them.