How much of a hash rate difference are there between these two cards?
Sapphire TRI-X R9 290 OC 4GB
Sapphire TRI-X R9 290X OC 4GB

I had a Gigabyte R9 290x OC4GB that I was only getting around 840Kh/s with and then it went dead.  So if I get a full refund on it then I'd like to stay away from Gigabyte this next time.