Was curious if anyone had much experience with R9 290's on subpar processors?

I've got a 2.8 GHz G1830 Haswell Celeron dual core.

I have 4x R9 290s.

After 24 hours, I'm getting about 1.4 cpd per card. 4ch is 116k, and 7 ch is 83. They are overclocked, 1400/985, as that seemed to improve the 7ch from 75 to 83.

Based on previous reports, this seems a little low? I'm running it -ss 2 for each card. CPU usage fluctuates between 50-67%.

Is this the norm, or should I be getting better numbers? What can I change to improve the cpd?