I was up all night working on tweaking my hash rate, when I first setup sgminer with the setting I seen posted for 280x's, I was getting around 4.5Mhs for my 7970 and 5.1Mhs on my 280x. Which seemed weird because I read a post where a 7950 was getting 6Mhs. I knew I was supposed to get more, it took a lot of trial and error but finally what did the trick for me was changing the intensity from 18-19 to 13 which then boosted my hash rate to 7.443Mh/s for the 7970 and 7.480 for the 280x running at 77.0C and 74.0C.