Electric Cost = $0.12 cents per KW
12 c / kwh is getting into *OUCH* range on electric cost.
The entire reason I moved last summer was that I considered 7.5-8c/kwh 9 months 14plus the other 3 months was way too high.
ETH is probably getting hammered because of the "2'nd and 3'd hard fork" issue, which are happening to cure the long-running issue with attacks overloading the network but some folks think any fork is a bad thing.
Even with that, *for me* ETH has been more profitable the last few days, abet it's close.
My electricity cost is basically "fixed" right now, but I'm in a rather odd situation for at least the next few months - but even if it wasn't, my electric cost is low enough I doubt that the power savings ZEC has would make up for the lower income *IN MY CASE*
Don't take anyone's word for it, crunch the numbers yourself because they DO vary.
I'm personnally mining at 0,18$/kWh, and that's still profitable. Of course says goodbye to 290 and such, but with RX 470, a little with R9 380 and 1070, I find a way to be profitable.
My 2 test rigs are 290s and 370s -- the 290s are really power hungry just like the 390s. The 370s uses very little power.
I still keep the 390s because of its powerful cores and big VRAM, however with new GPUs in the market, like RX series Polaris based architecture, not wise to buy any more R9s series, purely for low-power, supportability and sell-ability reasons.
My powerbill then was in sad state because of full on ETH mining. Soon after ROI of the 390s, expanding the farm with 480s and Nanos brought the power/hash/revenue ratio into positive territory. The 480s price point is perfect for mining. My next RX batch will be 470s to further reduce power consumption.
In this journey, lessons learnt in my opinion as follows, to share:
1. Undervolt. Undervolt. Undervolt. The Nanos and 480s are with modded BIOS and at -mV100. That saves me a couple of amps and a sizable wattage savings. Multiply that with 10 or 20 rigs, you will see the savings quickly.
2. Always spend a bit more on good PSU. I standardized on EVGA 1600, 1300 and 1000 - G2s Gold80s (10 year warranty). Total wattage consumed by each rig should not be more than 80% of the PSU specs. All this resulted in efficient power consumption, stable rig esp. 5 or 6 x GPUs systems. Less downtime, maximum hash time, increased revenue and no worries of power overdraw leading to frying mobos and expensive GPUs etc.
3. Mining software. Standardize on stratum compliant mining software for maximum hash. For ETH mining, stratum compliant pools will allocate the jobs efficiently to maximize your rig hash power. The early ETH mining software was based on POW... and this method resulted too many stales and rejects, wasting GPU cycles and power. To fix this problem, we had good proxy solutions like sammy007 which saved a lot miners. Then came Claymore - that guy is good developer. I studied his past projects, you know that this guy is good and smart coder because he had a big following even a few years ago for Cryptonight miner. The ETH Dual Miner v7.3 is by far the best performing ETH miner to date. The dev fee is well justified because miners consistently makes profit with his miner. I like the monitoring tools too - he has centralised the "ethman" to now monitor ETH, XMR and ZCASH -- you can now monitor 3 coins in ONE single dashboard. I use this dashboard extensively to provide overall information on the farm 24x7 to my home PC and also smartphone. Less stress - good life.
4. Temperature. I never tracked this matter seriously until one of the more experienced miners shared with me their experience recently. The basic components/equipment usually of good quality, acceptable industry specs, and good warranty are: GPUs, memory, SSD, motherboards, PSU.... however most risers, cables, switches, odd fans and other peripherals are often made in China, in some back alley somewhere without the warranty .... these are the parts that wouldn't last long under extreme conditions. Certain cables esp PCI riser cables will work fine in a good ventilated spaces... however under extreme conditions, it melts and certainly a big fire hazard. So too high of temperature being the root of all evil for miners... ensure that some form of temp controls are put in place. Remember, a faulty PCI riser means a inactive rig = no revenue. Also, dont worry about setting GPU fans to 99% because its easy to replace GPUs fans than to have a fried GPU.
sorry for long sharing.