I have built about a half-dozen GPU mining rigs, and I wanted to put together an Instructable on the easiest way that I've found to make a nice, tidy rig in a short time and for a good price. Here, I used the 4-GPU version of the enclosure but the 6-GPU version would give more hashing power if you have more GPU.

You can either use new or used PC guts for one of these rigs. Actually, a lot of GPU mining rigs use old, leftover PC motherboards and CPU's. Mining doesn't take much CPU horsepower, so pretty much any PC newer than Pentium II is a good candidate as long as it has PCI-express slots. The more slots the better. Here we're using a Gigabyte mobo for AMD Althlon II, which is still available at a good price new if you can't find one secondhand in a junkbox somewhere.

Here's what we'll be using today:

To house the rig, we're using a Minatrix GPU Rig Kit from Etsy - $36 plus S&H for the 4-GPU version.
Gigabyte GA-970A motherboard with AMD Athlon II x4 and 2GB of DDR3 RAM - $Free
EVGA 850W modular PC power supply - $89 on Amazon
GPUs of your choice. We've had great luck with anything AMD - R9 390x, RX470, etc - $Varies

We'll also need some wood glue and a short screwdriver. The first part of the build will be the construction, then the wiring and setup.

Please note that a couple different GPU types are shown during this install - you can also mix & match, or use all the same - it really doesn't matter as far as I've seen.

Let's get started!

Step 1: Get Familiar With Your Pile O' Parts, and Build the Shelf

The kit comes as flat-packed sheets, so the first thing you'll want to do is get a nice open space to work in, and maybe throw some plastic down to keep glue off your workspace. Here, we've unfolded the parts of the box to show the relative position of all the components.

First, grab the shelf panel and the small stabilizing spar, and flip them upside down. The spar matches up evenly with the sides of the shelf when installed properly, so do a test fit now to get the direction right.

Put some glue on the edge of the spar, and if you like - also on the face of the tabs that mate against the shelf. Go ahead and install the spar into the tabs at the front of the large holes in the shelf panel.

Double check that the edge of the spar matches up with the other tabs on the shelf panel - if it doesn't, the spar is backwards! Flip it around, it'll match up.

Now you can set aside the shelf panel to dry a bit while we work on other things.

Step 2: Installing Baseplate Motherboard Standoffs

Next, get the baseplate and the pile of motherboard standoffs.

There are a ton of holes in the baseplate to fit all kinds of motherboards, so the best thing to do is to put your mobo on top of the baseplate and find the ones that match up best. Here, I've marked my matching holes with a red sharpie. You can't just choose any holes randomly, because the metal standoff may short out something on your mobo if it doesn't meet up with a hole cutout - it's worth it to just set the mobo on top and mark the positions properly now.

Next, install the mobo standoffs by pressing/screwing them into the holes you marked. I usually put a dab of glue on/in the hole to keep the standoff from moving in the future.

I used to install the standoffs by hand, but it really hurts your fingers trying to twist them all the way in. Nowadays I put the screw in the standoff, screw the standoff into the hole, then grab the standoff with pliers and take the screw back out. This is much faster, and really saves the fingers.

Step 3: Building the Sides

Here I've laid out the baseplate and the two sides as if they were unfolded - setting it up like this ahead of time helps make sure nothing gets installed backwards. The tabs on the side panels face the back, same as the slot and tab on the baseplate.

Take the baseplate and slap some glue on the edges, and both top and bottom of the tabs. I usually do one side at a time - apply glue, then mesh the tabs into the slots in the side panels.

Do one, then the other. At this point, the sides will stay on but they will be leaning out a bit - this is exactly what we want, as it helps greatly with the next step. Let them lean out a bit!

Step 4: Install the Shelf Panel

Now grab the shelf panel that we set aside earlier. This piece mates into the slots that are halfway up the side panels. Keep in mind that the side with the spar is front, and the side with the cutouts/tabs is the back

Apply some glue to the edge and tabs on both sides of the shelf, then mate it into the side panels one at a time, inserting the long tabs and the small spar tabs into the appropriate holes in the side panel. Since the side panels were leaning out, this lean gives us a bit of room to work with.

Once you've got one side meshed in, it should stick in pretty tight and bring the box together when you mate the shelf to the other side panel. At this point, the box may be a little wobbly, but it's a box!

Step 5: Install the Back Panel

Now, take the whole box and place it face down so all the tabs in the back are sticking up at you. Apply glue to the recessed edges, and the tops and bottoms of the tabs. There's a lot of them.

Now we install the back panel. Since the box is a little wobbly, there's a chance that it all doesn't line up perfectly right now - don't worry, installing the back panel will finalize the alignment. We can use this wobble to help things fit in.

I usually start on one side, and make sure the tabs on the side panel are meshing in with the tabs on the back panel. Lay the back panel down, and next work to mesh in the tabs on the shelf and baseplate. Once those match up, the back panel should just pop down into the tabs on the other side panel and sit flat. Done!

You can use straps or rubber bands to keep everything together while the glue dries, but the easiest thing is to just tape the edges in place with blue painter's tape (or whatever tape you have). Set the box upright, and if it looks like the sides want to bow out or something - place it on it's side with a couple books up on top of the other side.

Give it an hour or two to dry, and you've got yourself a box!

At this point, you're free to do whatever you like. I typically paint, then wire so that's what I'll describe next.

Step 6: Paint the Box

A quick coat of spray paint will give the box a nice, uniform look. Let your kid paint it - they'll get a kick out of getting to play with spray paint, and it saves you some work! Flat black is very forgiving, lol!

Step 7: Install the Motherboard and Power Supply

Since we already have standoffs installed, you'll want to gently place the motherboard inside the enclosure so you don't scratch anything. It should be pretty easy to match up the standoffs to the holes in the mobo and install the screws, and a short screwdriver works wonders here! Once the screws are in, the mobo is held in pretty firm.

Next up is the power supply. Place it in the left hand side with the fan facing out. This should allow you to match up the PSU's hole pattern with the cutout in the back panel of the box. Some #6-32 screws will mount this guy into place as well.

Step 8: Initial Wiring

The motherboard needs the 24-pin power connector from the PSU, as well as a 4-pin or 8-pin power connector for the CPU itself. These cables are rather large and can cause tangles if flopping free, so after plugging in the connectors it's best to zip tie them to the ceiling to keep them out of the way.

Next, the GPU risers need power, most likely from SATA cables. Take one of your PSU's SATA power cables and zip tie it to the holes between each of the GPU positions at the front edge of the shelf plate. To get it lined up, simply fold the cable halfway between each of the SATA connectors and zip tie it at the folds.

Plug the cable to PSU, and if you have an SSD you can either mount it to the side panel next to the PSU, or just stick it in the empty space above the PSU as shown in the last picture. Make sure the SSD gets power, and gets a SATA connection to the mobo. Zip tie off extra cables to keep them out of the way.

Step 9: Add GPUs

For this build, we're putting all the GPUs on risers. To do this, we first connect a riser's power cable to our multi-drop cable we zip-tied up in the last step. Then, we simply plug a GPU into the riser.

Place the GPU and riser so the tabs of the bracket drop down into the hole cut in the shelf. You should be able to do this without the top of the bracket running into the back wall if you start at the front part of the hole. Then, slide the GPU backwards until the bracket meets up with the back wall. Now you can zip tie the GPU bracket to the slot cut in the back wall to hold it steady from wobbling.

Last, add the USB cable and 1x PCIE adapter, and plug the adapter into one of the PCIE slots in the motherboard. I usually put GPU0 (the one I hook a monitor to) into the x16 (long) slot near the CPU. Then GPU1 goes into the x1 slot next to the CPU and I work from right to left, filling as many x1 and x16 slots as the motherboard can hold.

Step 10: Boot It Up!

On first boot, connect a monitor to the motherboard's graphics output OR to GPU0, and flip the switch on the PSU.

Since we're not using a power button, you may need to momentarily short the jumper marked PWR or RST on the motherboard in order to get things started. To avoid this hassle in the future, go into the BIOS straight away and set the default power state to "Always ON". This will start up the PC when you flip the power supply's switch, or after a power outage - so it's definitely a must have setting.

As far as software goes, I have used EthOS and Windows 10 and I think they're both equally good. Win10 is nice because MS is allowing unlicensed usage, so it's quasi-free and provides a familiar and cushy environment to work in. However, one of your GPU's MUST use an HDMI dummy plug if you plan to run headless or Windows won't load the GPU drivers and it won't mine. Also, finding and forcing the proper drivers can be a hassle when using older GPU cards.

To install windows, get the MS "media creation tool" and make a bootable USB. Boot it and go.

EthOS is a bit more difficult if you're not a linux guy, but it's pretty robust. My suggestion is not to do everything through console, and to take advantage of the Ubuntu desktop you can access. After booting up, wiggle the mouse down at the bottom of the screen to show the desktop taskbar - the config files you need to edit are all linked in the start menu, and you get a fair OS experience even with the limited system you're given - browser and such.

To install EthOS, you'll have to buy the iso and write it directly to the SSD using the tool listed on their page. You can also run it directly from a USB drive, but I don't have much experience with that.

As far as miners go - I've had good luck with both ethminer and claymore, but I tend to prefer claymore single mining as it eeks out a few more MH even after the dev mining.