i'm almost at break point too. its getting to the point where i'm going to have to stop mining and wait for it to come back up.
http://i.imgur.com/mQipSU6.jpgFor what it's worth, I think you need to work on power optimization - if I read your chart right, you are pulling 702 watts to run 1.3Mhs of scrypt?
I run rigs that pull 686 watts for 1.8Mhs when using Bronze PSU's, and I am currently now purchaing Gold rated PSU's as they pull closer to 640 watts at the wall for the same setup. I still can't justify the increased cost of Platinum PSU's.
Have you explored undervolt your rig or invest in a better PSU, or different GPU's with a better power per kh ratio. Heck, with that power cost, you may want to explore ASICs, when they actually become more reliable.
+ You can change you power meter to day/night one.
Not sure which part of UK are you in, but in NI you can save quite a lot with this type of tariff giving that rigs are on 24/7.
+as mentioned above, your power consumption seems high, I have 1 rig with just 2 cards for the moment (7970) and mining 1.3-1.5 MH from 550W; another one in the same area (~1.8MH - 4x270x) draws ~790W
A.
