My results on lbry.
750 ti with o/c :49-50 mh/s
970 with o/c : 131-132mh/s
1070 with o/c (2000mhz core):222-224mh/s
7970-280x o/c : 50-51mh/s
290 with oc :66 -67 mh/s
Are you on windows?
Try to do something cpu intensive while mining. What happens to your hashrate? My 970's get a boost of 14% and hashrate goes up to 150Mh/s per card.
-edit- OT something wrong with your 290, should do at least 90Mh/s with public miner.
does not make any sense that gpu make more hash when you use more the cpu with soemthing else