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.
Which settings do you reach 150MH on 970s , mate ?
Core ~1495, power limit as high as it goes, cpuminer with one thread running in the backround.
Gpu load 92-98%, mc load 24%, perfcap reason pwr.
Thanks , but still can't figure how CPU miner affects the GPU miner , I have Intel XEON E3-1225 , which is quite good for tough work ... will try that scheme

It is a mystery for me too. I am running 4690k with that rig.