Hope this helps others that are having the same problem as myself.
Having tried most things that I could think of I've finally found this information (why didn't I think of this before).
This may help others that are using EVGA Precision Tool.
C.o.D. now runs smoother. % of use on both cards has fallen from about 70% to about 55% and the temps have fallen also from around 50--60deg to 40--45deg.
Should have thought of this earlier.
Use Precision Tool to limit frame rate target.
When I checked mine the frame rate was set to refresh rate. I've now lowered this to 35fps and have the results that I've been struggling to achieve.
Here is the link to EVGA's Precision Tool page with an instruction video, hope this helps.
By the way, I'm not using the latest patch/hotfix but have gone back to beta 18956.
Good luck.
http://www.evga.com/precision/