Episode 2: A Father/Daughter Guide to Open-Air Cryptocurrency Mining
Over the holiday season at the end of 2017, my daughter Alexa and I embarked on an adventure learning to mine cryptocurrency. We successfully set up a new PC and started mining. We wrote up a description of what we’d done and called it A Father/Daughter Beginner’s Guide to Cryptocurrency Mining. We got tremendously positive feedback on it after thousands of people read our write up. So, we decided to do it again!
After Alexa’s first taste of crypto mining she was hooked. We had determined it was feasible to make money at mining, but at such small scale she’d generate little currency. In fact, we estimated she’d be earning about $80 USD a month, after cost of electricity, and it would take nearly a year to break even on the cost of the rig. We decided we had to do better.
In looking at what we built, and getting some advice from friends, we realized that mining with a stand-alone PC, or even a fleet of PCs, wouldn’t provide the best return on investment (ROI). Instead, we now wanted to build something called an open-air mining rig. This article outlines what we did together during our three-day build project and outlines our projected financial results.
In summary, our new rig is earning a much larger amount, with higher energy efficiency and a dramatically faster break-even time. This guide should give you the information you need to build one yourself. Good luck!
Updated Results for Original Rig
For purposes of later comparison, let’s start by looking at some updated numbers for our original rig — which is based on a stand-alone gaming PC. We’ve now been running it for several weeks and have better estimates for earnings and costs. Also, the price of Ether has gone up somewhat, which changes the equation — for the better. Here’s our current status:
- Rig cost: $927.99
- Estimated Gross Earnings (from Nanopool calculator): $104.11
- Average power draw (measured by Etekcity Wi-fi Smart Plug): 163 watts
- Monthly power bill (assuming $0.10 / KW/h): $11.75
- Monthly net earnings: $92.36
- Estimated time to break even: 10 months
Key Learning From Our First Rig
We can sum up our biggest lesson from our first rig as: it’s all about the GPU. Our original system had an advanced Intel i5 quad-core processor, 8 gig of RAM and a 1TB hard drive. However, in looking at the Windows performance meters on the system, we were using almost none of that. It was the Nvidia GPU on the video card that was actually doing all the work related to mining. All the rest of that fancy computer gear was a waste of power and space. That’s a key reason our break-even period was so long!
This leads to the concept of running a single computer with many GPU cards. This minimizes the costs of components like CPU, main memory, hard drive, etc that aren’t useful, and puts the focus on the components that are key to doing the work.
The best practice developed by many miners is called an “open-air” system. It’s called open-air because you don’t even need a case for the system. This reduces costs, and helps with cooling. It turns out that cooling becomes more and more important as you scale up.
What We Built
Here’s a picture of our first rig (with the red lights) sitting next to our new, open-air rig (blue lights).
You can see they look very different! In fact, the new open-air rig is actually built on top of a wooden crate we picked up at Michael’s Arts & Crafts — not even at a computer store. Beauty was not the goal. This project was about brute efficiency.
Here’s a clearer close-up of the new rig to you can see all the parts:
Here you can see the key components (from left to right):
- Four high-powered video cards
- Motherboard with CPU, heat sink and RAM
- Power supply
Parts Selection
After some research, we decided to start with a bundle from an outfit called gpuShack, which specializes in kits for larger mining rigs. Oddly enough given their name, they don’t sell GPUs, but they do sell the other core items you will need for an open air mining rig. We selected a kit called the “MOBO/CPU/RAM/EthOS Bundle for Six GPUs”. This included:
- Motherboard
- Low-end Celeron CPU with heat sink
- 4 Gig of RAM
- A 16 gig USB stick with ethOS — a special-purpose Linux operating system set up for mining. Note that we won’t be using a hard disk. We don’t need one. We’ll boot right off the USB key.
Total cost of the gpuShack bundle was $229.
We then picked up the following items we needed through Amazon:
- A 1000 watt EVGA G2 SuperNOVA power supply ($199)
- A six-pack of 1x PCI Risers from BS Tools ($38)
- An EVGA “Superclocked” GTX 1070 GPU ($440)
We also spent about $10 on a small wooden crate we’d use in lieu of a case.
Day 1: Starting the Build
We decided that our first objective would be to get a minimally working computer — using the fewest possible parts. This way we could minimize possibilities for error, make some progress, and then move on incrementally.
Alexa started by seating the processor into the motherboard and then mounting the heat sink. Note, you’ll need some thermal paste for this, so make sure you have some on hand. We wound up having to make a special trip to Fry’s Electronics for $3 worth of paste and it slowed us down by over an hour!
She then seated the RAM onto the motherboard and ran the cable from the power supply to the motherboard. Note that the power supply included all the cables we needed to connect all the components in the system to power — which was really handy!
Here’s what the system looked like as it came together. Note that Alexa decided to use some gummy-style erasers as supports to keep the motherboard off the wooden frame. Seemed like a good idea to me so we went with it.
We connected the VGA adaptor from the motherboard to a spare monitor and we were ready to boot up. There is where we ran into an issue that stumped us for quite a while. We flipped on the power switch on the power supply, but nothing happened!
Here’s what’s going on, and it’s good for you to know if this is your first build. Since we don’t have a normal case, we don’t have a typical power button — like the one on the front of a PC. There are two pins on the motherboard that would normally be wired to that power button. Since we didn’t have one Alexa had to just short circuit the two pins with a screwdriver. Bingo! The system fired right up. Don’t believe me? Here’s a video that shows you how.
So, we hadn’t even loaded an operating system yet, so we wound up at the BIOS screen — which is just what should happen. This was a big milestone. We had a working computer and knew we were on our way. We called it a day.
Day 2: Getting Mining
In order to actually really get going, we needed to install a video card. This turns out to be really easy for the first card. Extract it from the box and plug it into the 16x (long) PCI slot nearest the CPU. Then plug a cable from the power supply to the top of the video card. At this point we put away the VGA cable we’d use to connect to the monitor to the on-board video and replaced it with an HDMI cable connected to the newly installed video card.
Next, we needed an operating system. The gpuShack bundle included a USB stick with ethOS installed. We slotted that into an available USB port and we also plugged in a keyboard and mouse.
We were ready to boot up. Remember, we have no hard disk. We’re booting direct from the USB stick! Using the short circuit with a screw driver trick we were booted up and running quickly! After a few minutes of startup we had a screen that looked like this:
As you can see, it recognized our GPU and started mining right away! The screen gives you some key info you don’t want to miss:
- There’s a quick start guide! (I won’t replay everything written there)
- Your passwords are set to a default everyone will know — CHANGE THEM!
Here’s the handiest tip we can give you that isn’t obvious from the Quick Start guide. Although it looks like you’ve booted into a character mode terminal, you really have a full GUI at your disposal. There’s a hidden Start Menu in the lower-left corner of the screen. Just move your mouse down there and it will pop up. This will give you instant access to the key config files and a web browser that is pointed to a remote monitoring app. You can use this remote monitoring URL even when you’re not near the rig. This is super useful.
Once we added our Etherem wallet address and Alexa’s email for a password to our local.conf file we were off and running. ethOS comes set up to use Nanopool by default. We were already using Nanopool on our old rig and now they both showed up on the same screen in our Nanopool console!
You can see our hash rate doubled from about 25 Mh/s to about 50 Mh/s, and you can see both workers now towards the bottom of the screen. We’d now doubled our earning power. Progress! Again, we called it a day.
Day 3: Full Speed Ahead
We now had a fully working Ethereum miner with roughly the same performance as our first rig. The big difference is that the new one was built to scale — while our previous rig was tapped out. At the start of Day 3 we headed to Fry’s Electronics in San Jose to get GPUs.
Once we arrived, we went to the video card section. Other miners had clearly been here before us. The shelves holding the high-end cards were stripped clean. Luckily, a sales rep was able to find three in the back. Unfortunately, the price had gone up from $440 for our first card, purchased a couple weeks prior, to $499 each now. Supply and demand in action!
Once we got home, it was time to add in the extra video cards. This should increase our hashing power by four times! We slotted the second card into another 16x long slot on the motherboard and attached the power from the power supply. After booting up, we immediately saw the second GPU go to work.
However, when we went to add the third GPU things got more complex. We only had two 16x slots on the motherboard. The other PCI slots were the small “1x” variety. For those, we needed to use the PCI riser cards we’d purchased earlier. A PCI riser card kit will include a few parts: the card, a USB cable, a SATA power connector and a small interface card. It’s kind of a crazy collection of parts until you realize how they fit ogether.
Here’s a quick video that shows you how to put together a PCI riser. Once you have the riser built, you’ll plug the video card into the big slot on the riser, attach the SATA connector to the power supply and plug the small interface into the 1x PCI slot on the motherboard. Then you’ll need to run power to the video card from the power supply — just like you did for the other cards plugged into the 16x slots.
Here’s where things got tricky. When the system came up this time we got this screen:
You can see, two of the GPUs were running full blast, but one was only going at about 10% speed. We spent quite a while debugging this. In the end, we unpacked another PCI riser kit, built it and reconnected everything. This fixed the problem. I think we had a bad PCI riser. We threw that one away. They’re only a few dollars each.
After installing the final video card, which went smoothly, we let it run and then checked our Nanopool stats. Our earning power was now five-times what it had been with the PC rig alone.
Cranking it Up
Every serious miner takes one more step. You need to fine tune the GPUs. Remember, these are video cards that are built to play games. To use them for mining you will want to tweak them. You’ll want to minimize power usage and maximize speed. For Ethereum mining, this means you can reduce power to each card, lower the core usage on the GPU chip and increase the clock rate of the GPU memory. We added the following lines to a local.conf file:
globalpowertune 125 #sets power draw for CPUs to 125 watts
globalmem 4350 #increase clock rate on the GPU memory
globalcore -150 #reduce the number GPU cores in use
After saving the local.conf file, you need to move to the command line and run the following command:
sudo ethos-overclock
The new settings took effect almost immediately and the effect was clear. The hash rates on each GPU went from about 26 to almost 31. Here’s a chart that was automatically generated from the ethOS monitoring app for the rig. We’ve added the red text to show what happened at point during the day. Over on the right side you can see that the overclocking got us almost as much boost as a free GPU!
Results
The open-air rig proved to be a more costly, but overall a much more efficient venture. By removing all non-critical components we were able to cut costs associated with the unnecessary parts of the PC Rig but still get the hashing power of several GPUs.
This build did require more time, and trial and error than setting up the original PC rig, but it will pay itself off much more quickly. Break even time is cut almost in half and the overall profit is over four-times higher each month.
