Just throwing this out there. Bitmain mentions running the S5s with a 9 volt PSU for better efficiency. Has anybody tried this on a S3? Would it be possible? Would be nice if we could just plug in a 9 volt PSU without having to do any internal mods to the S3s. Of course I dont know whats required to run the S5s on 9 volt either.
I run my miners off adjustable power supplies. Right now I'm for the first time taking a Kill-A-Watt and measuring the stats at the wall for my two S3's, two S3+'s and single C1.
The Kill-A-Watt had been on the C1 for 1097 hours, used 921KW.
The two S3's need some explaining. I bought those on Amazon before I realized the advantage of buying directly. The first from CryptoCrane in the mid-west was excellent. The second from Pines Computer in Florida was a dog in a box that had been opened on the bottom and resealed, having two crappy hashboards. I should have returned the S3 to Pines Computer and taken my Amazon refund but instead I opened it up and re-applied heat sink compound. Still ran lousy but now I had worked on it. I ended up taking one board out and putting it in the good miner from CryptoCrane and now both run about the same, each having a board that's not so good, one coming up with an x and the other coming up with a - , both running in the high 420's but constantly dropping and getting restarted from a short program.
As I said I'm in the process of measuring stats of the 5 miners. I put the Kill-A-Watt in the S3 from Pines because I had to reboot it due to a 0000000- 00000000 chain. After an hour it was running at 389 watts, 4.84 amps. I should note that includes a small 120vac fan I picked up at Walmart and point in to the intake fan. I have one of those on each S3 and they both have a single bad board now.
I check the S3 from CryptCrane (now having one of the bad boards from Pines in Florida) and see 399 watts at the wall and 4.72 amps but it hasn't been running an hour since putting in my one Kill-A-Watt.
After I get stats on all my miners, stats for at least an hour's duration, I'll see what the lowest level I can reliably set my variable supplies to and try running the Pines for an hour on the Kill-A-Watt. I can probably get 10.5vdc for a test.
I'll get back to you on if the lower supply voltage shows a significant change in at the wall wattage.I have considered measuring the dc current in but I would use a 25 watt 1% .1 ohm resistor and if I'm getting 85% efficiency from my supplies then the 4.84 watts@120vac, PF .66 or 31.68 amps @12vdc, I squared R will be 100 watts so no go with the .1 ohm 25 watt resistor. I was thinking of buying shunts from China but then why. I'm scraping to keep these running with economic effectiveness.
I'd like to see somebody in China offer 50 amp and 100 amp shunts having small parasitic digital readouts. With those my balancing power supplies would be a snap.
soy
The second S3+ is running its hour so meanwhile I dropped the voltage on the S3 from Pines down to 10.23vdc, min I could get for now but will be able to get down to low 9v's with a resistor change. More and I'd worry about the supplies. There's no Kill-A-Watt on it but it seems to be running, albeit at a lower hashrate. ...later - up 27 minutes and the hashrate has picked up to 440GH/s avg. but it usually runs almost normal for an hour or two then drops and right now it's cooling. So, I'm going to shut it down and see if I can get it running at about 9.5vdc with the Kill-A-Watt.
...nuts, could only get it down to 9.9vdc given my available options without breaking out a soldering iron. Wake up is 401 watts compared to wakeup at 12vdc and 389 watts. First blush says no power savings from reducing the voltage into the miner. One would expect something given the fans run slower. But fans are pulse width controlled and if the pulses are wider but at a lower voltage this might mean higher current? DC motors run more efficiently at a higher voltage don't they given a better back emf?
I think my next step is to drop the voltage in on one of the S3+'s and look for a power savings. Then put the good board back in the first S3, the good one from CryptoCrane and get the two sucky boards back in the second S3 from Pines Computer in Florida selling on Amazon. I'll look to see if there had been any mods to the voltage regulators, and check the ASICs are correct. I'll measure resistor values at the voltage regulators but my guess is China realized Pines is a slock shop and sent them a crappy product.
Just went back and corrected the wakeup voltage of the S3 at 12 volts to 389watts and after an hour it was drawing 390 watts. So, the wakeup at 401 watts @ 9.9vdc looks like a 3% power increase.
Interesting - the 9.9vdc is causing one of the boards to give me a fan speed of 15300 while the other fan is 1560. First time I've had a fan speed an order of magnitude high.
The 12v 1hr stats were 390watts, 4.84amps, 120.6VAC, .66PF, 583VA $238/year
The 9.9v 1hr stats were 400watts, 5.00amps, 118.9VAC, .67PF, 594VA $256/year
I'll let it run like this overnight and see if the stats settle. Wall voltage changes with neighbors returning home after work and dinner getting cooked. A 7.5% cost increase per year. Interesting to see if it effects the hashrate drop. Really wish I hadn't put one of the bad boards in the good miner right now.
Of course I'm taking my supplies out of their comfort zone. The miner efficiency may have improved while the supplies' efficiency dropped. Can't really tell without high current shunts.
-------------
Now having shut down the first S3 from CryptoCrane in the mid-west and the second S3 from Pines Computer in Florida (open box at bottom and resealed, two slow hashing boards), and having put back to original configuration of 2 good boards in the unit from the mid-west, I've fired up the good S3 while set at 12.0vdc for a 1 hour run. I'll take readings then raise the voltage to 12.6vdc and give it another hour. Meanwhile I'll carefully clean and rebuild the S3 from Florida with its original slow boards. I plan to take some time and measure that resistor dictating voltage on the 8 regulators. Kind of does reflect life. So many aged retirees in Florida ripe for the picking by scam artists and street people living rough in the warm weather, crime is high. They elect politicians that claim to represent law and order. Such a high rate of criminals on TV tracked down have some history in Florida. The BFL honcho got convicted of postal mail fraud in Florida. The criminals range from street people all the way up. Texas likewise. If a Florida politician gets elected to a national office in 2016 expect the middle class economy to be impaired similar to my mining with the crappy S3 from Florida.
The good S3 is running and reading taken without the external 120VAC fan. When the slow S3 is up I'll put both fans on it but its reading aren't useful.
-------------
Before putting #2 (from Florida) back together, I checked some resistors for consistency. R14 as measured from the gold pad to the junction of R14 and the capacitor was consistent on one board and generally 2% lower than the other hashing board and the higher measuring board had a greater variation among the 8 resistors. So, for the highest measuring resistors I took a #2 pencil and brought the highest down to a consistent average that being 2% higher than the other board. Time will tell if one of the two boards improves.
---------------
Decided to take a 3rd reading of the good S3 but at 9.7vdc. Interesting result at wakeup - both fans read an order of magnitude high. Two good hashing boards.
--------------------
So, for my setup, with 12vdc datum, these are the results:
12.0vdc datum
12.7vdc cost 104%
9.7vdc cost 107%
Clearly I should run at 12vdc and look elsewhere for efficiency.
soy
Fan speeds now within correct ballpark range - this at 12vdc. So, fan speed an order of magnitude high - it's the power supply.
