This plastic bin, open air case accommodates a minimal setup, i.e USB boot, no hard drive, no CDROM. I have put together two of these so far and they are serving their purpose well.
(9) M3x10 pan-head machine screws 0.40USD
(9) M3x20 standoffs 2.00USD
(9) M3 nuts 0.50USD
(18) M3 washers 0.45USD
(1) stackable plastic bin 6.00USD
(16) 180mm length zip strips 0.60USD
Tools: scissors, screwdrivers, wrench, cutting/sanding tool (dremel)
Get a stackable ventilated plastic storage bin. The bottom should be big enough to comfortably hold your motherboard and it should be deep and tall enough to accommodate your GPU + fan and allow for some airflow. I saw the one below at my local hardware store and it turned out to be the perfect size.http://i1113.photobucket.com/albums/k508/crispining/TheBox.jpg
Place the motherboard in the bin. Keep in mind future placement of your ethernet line, USB, GPU hookups, etc and adjust accordingly. Use an indelible pen to mark where you will need to drill your motherboard standoff holes. Remove motherboard and drill your holes. I used a 3.1mm drill bit to allow for my M3x10 machine screws to fit.http://i1113.photobucket.com/albums/k508/crispining/PositionMotherboard.jpg
I placed my M3x10 screws with washers on each side from the bottom and loosely secured them with the female end of the standoffs. The male end of the standoffs then protruded up through the motherboard. So this is upside down when compared to a regular computer case setup. It allowed me to place my motherboard in the bin securely, yet temporarily for other steps in my build.http://i1113.photobucket.com/albums/k508/crispining/StandoffsInstalled.jpg
Carefully check to see if the standoffs properly align with the motherboard standoff holes. If not, it may be possible to adjust them to fit since they are only loosely connected at this point. If they fit fine, then go ahead and fully tighten down the standoffs to the screws. If they are too far off, you may need to find the problem and drill a different hole. Make sure you don't torque your motherboard!!
With the motherboard placed on the standoffs but not yet secured, check the gills of the bin and trim away any gills needed to plug in your ethernet, USB, keyboard and mouse. For my bin, the plastic was soft enough to simply cut with scissors.http://i1113.photobucket.com/albums/k508/crispining/MakeAccess.jpg
To make the exhaust vent for the GPUs I temporarily placed a GPU in the outer and then inner slots and used an indelible pen for each placement to mark cutting points on the back wall of the bin. http://i1113.photobucket.com/albums/k508/crispining/MarkCuttingPoints.jpg
I also took the opportunity to mark off the video connection on the front of the bin and cut another ventilation gill with scissors. http://i1113.photobucket.com/albums/k508/crispining/MarkforGrinding.jpg
I then removed the GPU and the motherboard from the bin and placed them safely away to protect them from flying plastic shrapnel while I cut the hole in the back of the bin with a dremel cutting disk. Cutting really produced a lot of tiny plastic bits that could have caused any number of connection issues with the various components if they had found their way into something.
I used the dremel with a sanding drum to clear away unneeded material from above the ventilation gills to allow for the video output connection to a monitor. After making all the cuts and trimmings I cleaned the dust and debris off of the bin.http://i1113.photobucket.com/albums/k508/crispining/CutsMade.jpg
I placed the motherboard once again back on the standoffs, this time securing it to the bin with M3 nuts. At this point I added my CPU, RAM and connected the motherboard power cables in preparation for the power supply. (The PSU can be seen already attached in the photo. The next step describes securing it to the bin.)http://i1113.photobucket.com/albums/k508/crispining/MotherboardInstalled.jpg
With adding the power supply I used 8 180mm zip strips - 4 on each side to make two square straps to hold the PSU to the outside of the bin. Make sure that it is properly fitted to the side to allow enough air flow. In my setup, the intake fan is facing away from the bin and the exhaust is facing to the front. In hindsight, I think 16 zip strips would have been better. (They can still be added with no problem.) That way there would be some redundancy to keep the PSU safe in case one of the ties should break. While making my first setup I had one tie break and the whole PSU broke free. The zip strips fit really nicely through the ventilation gills of the bin. When connecting the power cables to the PSU, take care to support it from the opposite side so that the zip strips don't snap. Also, make sure that any excess from the strips is trimmed away and not interfering with any moving parts of the computer.http://i1113.photobucket.com/albums/k508/crispining/SecurePSU.jpg
At this point, I added my GPUs and finished making my other connections. Using some extra zip strips. I tied off the power cables to keep them out of the way of airflow where needed. With my first case, since the GPU power cables connected from the top of the card and since there are 4 cards right next to each other, I was able to add a 200mm fan on top of the cards and a 140mm exhaust fan at the back of the bin and I took off the mounting plates (not the plastic shroud) in order to facilitate more airflow for keeping the GPUs cool (pictured below). Also, with my first case, I was concerned about the exhaust hole weakening the structure of the bin too much and so I didn't cut a complete hole. Because of this some exhaust is blocked and one of my cards runs warmer than the others. I am almost certain that if I make the exhaust hole similar to the one pictured earlier in this guide, that card would run about 8C cooler. It may even be possible to remove the exhaust fan entirely to save on noise. As is, I have 4x 6790s OC at 950/850 with temps from ~ 58-74C. In my bin pictured in this guide, I so far have only one GPU and I am awaiting 2 more.http://i1113.photobucket.com/albums/k508/crispining/FinalRigsStacked.jpghttp://i1113.photobucket.com/albums/k508/crispining/RigsfromBack.jpg
I made the same mistake I think a lot of others made when first getting into mining; I bought an actual case and had issues with overheating cards. I hope this helps save a little money for anyone building a new rig or getting into mining in general. If you feel this was worthwhile to you, please feel free to make a donation. Good luck in your endeavors!
Donation address: 1PqTM8XXbs4yWaQy3n8Pg12SXAFZUVqrdZ