I ran the little test with old rx 370 and hd 7970 cards with version 032q - worse than clay 11.3. 4x370 - 1.4kH, 5x7970 - 2.2kH; in the claymore 1.7kH and 2.4kH. No optimization with old videocards?
Probably you didn't wait enough to recieve max speed. For full speed you need to wait about 10-15 minutes on JCE.