On Bitcoin Mining 5

It turned out that we would not be in my sister-in-law's house as long as previously thought. They were returning home and we needed to move out to a townhouse that we owned by January. This meant that I would not be able to bring the BFL Monarchs with us. For one thing they were too loud for a townhouse environment and too hot. They were also not very efficient in terms of electricity consumption. They are rated by BFL for 0.65 to 0.85 watts/GH but I measured them as using close to 1 watt per Giga hash including the power supply and the necessary laptop.

Bitmain Antminer U3 version 2

Looking for quiet, townhouse friendly miners, in October I bought two Bitmain Antminer U3 miners. This ASIC miner is very similar to the Rockminer R-box 1 (37GH/s) miners. The U3 however runs at 55 to 62 GH/s. Like the older Rockminer, the U3 is basically silent and put out little heat while using about 50 watts of power (plus wattage of attached computer). The problem is that every day or so these miners would become "zombies" meaning that they would stop working. This requires a hard reboot of the device (unplugging and re-plugging) and restarting the mining software. It's a hassle and not on a schedule of any kind so you don't know when you'll have to do it. So as quiet as this was, the fact that it had a problem like this and that I felt the hashrate was too low I kept looking for a better solution.

The better solution in my situation was the Black Arrow Prospero X-1 (X-1.5). The X-1 hashes at 100 GH/s or better and the X-1.5 hashes at 140 to 190 GH/s. This miner is unique among ASIC miners - for one thing it has a large fan which dissipates the generated heat very quietly and effectively. For another thing it has an Android-based touch screen for interfacing with the miner. The miner is also WIFI capable which means that you can place it anywhere in the house and it doesn't need an ethernet cable or a computer attached to it to run the mining software. It is truly a stand-alone device. Perfect! As it got closer to moving day (again!) I sold the two Monarchs which turned out to be pretty solid hashers - if a bit inefficient - and bought two Black Arrow Prospero X-1.5s. I also sold one Antminer U3 and kept one in the box as a backup. I ran the two Prosperos near the dining room in the townhouse for most of the winter and spring of 2016 and appreciated their silence and their heat generation. 

The nice thing about mining for Bitcoin at home is that for part of the year the heat that Bitcoin miners generate can (and is) used to heat your living space. One hundred percent of the heat generated will go into the air in your home. For instance, if my two Prosperos raised the temperature of the downstairs portion of my townhouse by two degrees Fahrenheit, then that is two degrees that didn't have to be heated by the furnace (electric blower and gas fueled) thus saving that much electricity and gas from being used to heat our home. This means that the efficiency of the miner doesn't matter very much in the winter or on cold days in the spring and fall because you are basically running a heater that is mining Bitcoin. It's another story when the hot weather comes but the efficiency of Bitcoin miners is going to be better than rated over the course of a year if they are used in environments where their heat is used. (Now if they could make Bitcoin miners that generated cold air we'd be all set for the summer!)

I'll cover my experience with Bitmain's Antminer S7 in the next On Bitcoin Mining.

On Bitcoin Mining 4

To continue the story from On Bitcoin Mining 3, in early 2015 I had a stack of 6 Rockminer R-Box 2 110 GH/s Bitcoin miners in my living room (which my wife didn't complain about as long as I kept them quiet) and while the heat they generated was appreciated in the winter and reduced the gas bill somewhat, it was now late spring and some of the days were mighty hot which in turn made the living room too hot. So, it was either turn off the miners (which I did do on many days) or relocate them. I decided to try the attic and add an external fan.

The attic had a pull-down stairway which made access to it easy. As you may know, attics get hot on warm days and this one could reach 120 degrees Fahrenheit (49 degrees Celsius) or more. For this to work safely I had to set things up right. I placed the miners in stacks of 2 on non-flammable porcelain tiles, placed the power supply also on a porcelain tile, aimed them all towards the center of the attic where their heat would rise to the roof vents and aimed a fast blowing fan at the back of them. I also replaced the quiet fans I had earlier installed with the original more-noisy-but-more-effective-at-cooling-fans back on the miners. Then I monitored the temperature of the attic and monitored the temperature of the miners. On cooler days and at night the miners ran from 50 degrees Celsius to 65 degrees. On hot days the miners would run in the 70s. If they approached 80 degrees (which they did on really hot days) I would shut the miners down. This setup allowed me to mine in the summer and the noise and heat were out of sight. The down-time was minimal.

Oh, and I almost forgot about the laptop PC which I had to have attached to these six Rockminers. This laptop had to be in the attic too since the miners are attached to it via USB cords and the software on the PC runs the miners. After some research into the operating temperature of laptop lithium batteries I opted to remove the battery from the laptop and allow it to run only on AC power. It certainly wouldn't be good to have a rechargeable lithium battery exploding in the attic. 

Of course, this is not an optimal setup and if you are careless maybe even dangerous. Miners can fail if they run too hot too long. But these miners did not fail, and did not run slower. I kept them under 80 degrees and they only had to last until August like this as we were moving into my sister-in-law's house to take care of it while their family had "moved" out of the country for what was supposed to be a couple of years.

This meant I would have a basement in which to place my miners and in a solar-powered house. Nice. Hello, almost-free electricity.

BFL Monarch 650 GH/s Bitcoin Miner

At the same time I had noticed that the prices had come down on the water-cooled Butterfly Labs Monarch 650 to 700 GH/s bitcoin miners. If I got just one of these it would replace the six I had and give me the same hashing power. I bought one of them off of eBay and plugged it in. I had trouble getting it to hash at the rated speed. I was only getting about 500 GH, not the 650 advertised. It turned out that I had to use a special version of the Bitcoin mining software BFGminer. Anyway I spent dozens of hours trying to work out the problem. Butterfly Labs' own software EasyMiner never worked for me. Finally I got everything ironed out and the thing was running at 650 GH/s. I decided to get another one of these (actually a 700 GH Monarch) and sell the 6 Rockminer R-box 2s. 

Due to the fact that the Monarch's are liquid-cooled, the two fans on the miner are not as loud as fans on many other miners (like the Antminers). They are also potent heaters and the basement was soon very warm. This wasn't an issue though because it was a basement and not a living space.

This is the 1300 GH/s setup I had in the late summer of 2015 and going into the fall. But, as ever in the world of Bitcoin mining, things never seem to stay the same for very long. More to come....

(Some Black Arrow Prospero Bitcoin miners for sale here)