CMT4GX3M2A2000C8 - Corsair Dominator GT 2000C8 on P67

I think my better kit needed 1.8V for 2500 7-11-7 but I don't remember exactly.
I'm not using PSC for some time. New IC are usually giving better results on Intel platform so for benching I'm using something else.

I can make 2500 7-11-7 @1.75v but its not stable and crashes on any sort of load, if I get time to play I'm sure they should get more stable with a bit more voltage

Try 8-11-8. If you are running IB then performance will be about the same as on CL7 or even better ( results were in my IB oc guide ). You can probably go up to 2600 at CL8. Depends from IC, voltage and cooling should be 8-11-8 or 8-12-8.