My latest mining project uses an eight card Octominer motherboard. It includes a scalable and affordable open air frame idea I have been playing with. The parts used for the build are:
[Motherboard]: Octominer B8Plus $214.05
Ram: Micron 4GB PC4-19200 DDR4 2400MHZ 260 Pin SoDIMM $39.00
Processor: Intel 3855U (included with mobo)
Drive: SanDisk 16GB Flash Drive $7.99
OS: Simple Mining OS (free)
PSU: HP 750w with Rev7 X-adapter from Parallel Miner $64.00
GPU: Zotac 1050ti Mini (eight ea.) $239.00
Cooling fans: Cooler Master 140mm (3 ea.) $6.75.ea
Frame End panel: Suspended light ceiling panel $5.33 (can get three rigs from ea. panel)
Aluminum Extrusion: C-Channel (2 ea.) $8.64 ea.
Epoxy: Two part one minute epoxy $4.39
Hex Spacers: I had some, but these should work (get some screws too!) $5.00+/-
Total cost: $2300.00 +/- As you know the prices in Crypto, especially for GPUs vary wildly!
I have had fairly good luck using risers for my mining rigs (three bad out of 42 so far), but seeing the Octominer board that would carry eight gpus with no risers seemed like a great way to go so I started this project to see how it would work. GPU prices being what they are I have been holding off on buying any as I wait (hope) for the prices to come down or some weak hands to bail and dump their hardware on Ebay. As I obviously would need some GPUs for the build I decided to go with the Zotac 1050ti minis. The Zotac brand has been very good in my experience, and I was able to get seven of these for $240.00 each, and the eight, an "oc" version was $260.00. Still too much for what the cards are IMHO, but the market is what it is, and I like to keep busy building things.
The Board
The online help at Octominer's website was great with one exception. Apparantly a new guy was manning the chat and was not able to help me with an OS question, but it was no big deal as the next time I logged on I was given correct answers to all my questions. The site only accepts crypto for payment, not really a problem for me as I prefer that method, but be aware if you want to use Paypal or CCard, you can't as of this writing. (3-25-2018). You do get a $9.95 discount on the price for any inconvenience this might cause you. The shipping is $25 from China, and you have to wait for the next batch to ship out. In my case it was not long at all. I was contacted for a phone number to give to DHL, which should have been a part of the original order process I think.
The set up of the board was super easy. I plugged in the ram (a bit finicky as I was not used to this type memory), a vga monitor (no hdmi on the mobo) and the PSU connectors (5), and it booted to bios using the delete key. I made no changes to the bios, just looked around. Next I installed two of the GPUs just to see what was what, and the system again started right up, loading SMoS from my flash drive without a hitch. When I put all eight cards in, same thing, no problems at all. I like this board a lot!
The Frame
I really like the aluminum frames I have been using for my six card riser rigs, except for the cost. When I first started building miners I checked into buying the components and fabricating the frames myself, and there was no way I could do it for the price these were selling for. That did not include the time it would take either, so the $99.00 to $120.00 I was spending for these frames was actually not so bad. There is an option for a frame made to fit the Octominer from Spotswood which looks very nice and costs about the same as these kit frames I had been using. Still, I had a nagging feeling that there should be a a less expensive way (not wood) to build a rig frame. The Octominer project was a perfect chance to experiment as the problem of mounting risers was eliminated. I wanted to use inexpensive aluminum channel instead of the pricey extrusions and connectors from 80/20 and the like. I love their extrusions and connectors, don't get me wrong, but I cannot justify the expense. When i first started visualizing a way to suspend the cross pieces to support the components I pictured solid end panels from plexiglass which I woud then attach the channel ends to somehow. I was going to figure out a way to do this, but in the meantime wanted to start locating the channel to get an idea of the size. I remembered using these plastic light grids in contruction projects and picked one up because the grid would be a simple way to experiment with locating the channels to end up with my final size. As I started playing with it, I realized that the grid would be the perfect end panel itself.
Sizing
The openings on the grid are a little over 1/2" square, which makes them a little larger than the 1/2" x 1/2" channel I was using. I considered trying to screw them in but the plastic is too fragile for that. I then considered using a hard setting hot glue, but I was afraid the bond to the plastic might break when flexed, and really any excuse NOT to use the messy hot glue is fine with me. So that led me to epoxy. The two part fast setting stuff I used is very strong, comes with two mixing nozzles that let you shoot the goop into the small openings around the channel, and is very fast drying. I used a five minute version on the first attempt, and it was just way to long as you need to hold the ends square to the horizontal plane as you assemble the frame. The one minute worked just fine. I clamped the pieces down at the proper distance apart and then held them against some square blocks to keep the shape where it needed to be. The bars spacing worked out quite well using the 1/2" grid, needing only one small cutout on the interior portion of the end panels to allow for the mobo mounting bars to sit correctly. After adding a few bars the frame starts to be very rigid and easier to work with. I wanted to mount the PSU to the two rear bottom bars with velcro to allow easy removal and access to the power button and connectors. I mistakenly spaced the bars 1/2" too far apart and had to use some spare plexi strips to sit the psu on, still using velcro. Better marking on the grid would have eliminated this error. To mount the mobo I used some spare spacers and screws from the riser frame kits I had (these kits came with tons of extra hardware). Having determined the length I needed (21.5" worked well for this build) I hack sawed the two 96" pieces of channel into eight cross members. I laid two channels on a table with the mobo located on them and marked the mounting holes with a sharpie. It was easy to drill and mount the spacers as stand-offs for the board. The same process for mounting the fans worked with the supplied fan screws. I just drilled a clearance hole and threaded the fans onto the channels. The gpus were attached with some #6 x 1/2" sheet metal screws in pre-drilled holes. I got these holes wrong the first time. It is easier to go for the side slot than the end on the gpu mounting bracket. This lets you insert the card and then tip it sideways onto the screw with some leeway for making the card straight. Some thought as to the orientation of the channel opening is required before the epoxy to end panel operation. The addition of the fans and mobo made the assembly really strong as the components acted as shear panels to brace the frame. Any concerns I had about the frame being flimsy or flexing were gone when I was finished. I could easily pick up the fully assembled frame with components and carry it around with no issues. It was very strong in fact.
Power, Sol/s and Dollars
The Octominer needs at least two of the 6 pin connectors to operate. I was told the Mobo with processor uses 30 watts. With the cards installed all five mobo connectors must be cabled. I have the GPUs left to max power which is 75 watts each, and these 1050ti's require no additional cabling as they get all their power directly from the pcie slot. The three fans use 1.68w each, which I connected to one of the breakout board 6 pin outlets. This gives the rig a total power consumption of 635 watts, or $1.50 a day for my utility. The rig mines at about 1500 sol/s so at today's rates it would take a couple years to roi with these cards. (ouch) The rig did bring in about $120.00 a month mining Zcash however when first built, and that left a net profit for some cash flow. That $75 a month profit is more than the $2300 would make sitting in a savings account, and it is a lot more educational and fun to build mining rigs than to watch a bank account. The use of the riserless rig is a huge improvement in my opinion. The cost for my "standard" builds (if using only one 750 watt ATX psu) without GPUs is $552.00 plus some shipping. The Octobuild without cards is $388.00, a $168+ savings, and no risers to fuss with. The crate endwall frame let's me extend the size to accommodate any card length easily, so I plan to go this route on my future rigs.