Open Frame Mini ITX PC

I've been wanting to build a small desktop PC for quite some time. I also really liked the idea of an open frame test bench style chassis- something that would allow me to easily remove/replace components.

My requirements for hardware were primarily based around content creation, 3d modeling, photo editing, and CAD work. I do enjoy occasional gaming but that wasn't a priority for me.

With that in mind here is the hardware breakdown:

Processor- I went with an AMD Ryzen 7 2700 8 core. For a while these could be purchased for $150 or less, which is pretty fantastic deal. The Ryzen 5 1600AF is another awesome deal since it's essentially a Ryzen 5 2600 for under $100. If you need PCIE 4.0 for fast hard drive access then you want a 3rd gen Ryzen. For 3rd gen Ryzen the Ryzen 5 3600 is a great all around buy.

Memory- RAM is highly dependent on the motherboard you choose (be sure to check the manufacturer's QVL sheet) but with Ryzen I've had good luck with G.Skill. I used 16GB (2x 8GB) G.Skill Flare X from my old PC build. Higher speed RAM does offer an advantage with Ryzen but you get to the point of diminishing returns quickly.

Motherboard- I chose the Gigabyte X570 Aorus Pro Wifi. With mini ITX motherboards choices are a bit limited. With Ryzen your choices are B450, X470 and X570 series. B450 are the most affordable. X470 isn't really that compelling since it only really allows for running dual graphics cards, which isn't used in the min ITX format. Sometimes X470 offers a bit more power delivery for higher core count processors. X570 offers PCIE 4.0 when used with a 3rd gen Ryzen processor as well as better power delivery and greater RAM capacity (B450 and X470 max out at 32GB RAM.) I wanted to be able to use dual M.2 hard drives and that limited my choice to either Gigabyte or Asus. Asus offers dual M.2 on its B450, X470 and X570 motherboards- the B450 would have been my first choice but it was always out of stock with long lead times. The Asus X470 didn't make any sense price wise since it didn't really offer any advantage over the B450 (except maybe looks.) The Asus X570 is super nice but the price was significantly higher than the Gigabyte board. The Gigabyte board had the best combination of features and cost I could find and it's good to go when I eventually upgrade to the Ryzen 3900 series processors.

Graphics card- I went with the EVGA GTX 1660 Super. Trying to keep the PC as small as possible meant using a graphics card under 200mm in length. Since my monitor is 1080p and I'm not a super gamer I didn't need a high end card. For 1080p the 1660 Super is probably the best deal out there in a small card around $200. The RTX 2060 didn't really seem worth it to me for the$100+ cost increase. If you want a small workstation card the AMD Radeon Pro WX5100 is probably your best bet. If you're going to build a Hackintosh get an AMD Vega 56 Nano or a RX 570/580 ITX card off eBay or Craigslist- newer ITX size Radeon cards are non existent right now. PowerColor lists a RX 5500XT ITX size card as well as a RX 5700 ITX card but I don't think anyone has actually ever seen one.

Power Supply- I used my old EVGA 450W ATX power supply. Your choice in power supply will depend entirely on what processor and graphics card you choose. The more modern graphics cards have significantly less power draw than cards of a couple of years ago. I will say that with a build like this full modular power supplies are definitely the way to go.

Cooler- The stock AMD cooler is pretty good. If you're going to overclock or have intentions of installing a Ryzen 3900 series processor then Noctua coolers are tough to beat and the NH-DH15 is the king of the heap. It's nearly dead silent, will last forever, and it looks killer in black.

Hard drives- This is often a matter of personal preference. The Gigabyte board offers dual NVME drive compatibility so I used my old Samsung 960Evo along with a Sabrent Rocket. The Sabrent drives are very competitively priced right now. For a larger storage drive I'm using an Adata SU800 2.5" SSD.

When purchasing PC parts I use PCPartPicker to locate in stock items at the best price and check system compatibility. Always read through motherboard manuals and product data sheets to confirm compatibility- this can save you a LOT of headaches later on!

Tools/materials needed:

You really don't need much in the way of tools to build this. A drill press is really nice as you need to drill accurate, straight holes.

You'll also need drill bits to drill proper size holes for drilling, tapping and countersinking 6-32 socket head cap screw bolts.

I used a 3d printer to print a 2.5" hard drive mount as well as a cover for the power switch but the hard drive mount can be purchased online.

You'll also need a power switch and some cable sheathing (just to make it look pretty.) Note that this power switch is just barely long enough for the threads to stick through the .375" thick Aluminum plate.

Please be sure to read this all the way through and look at the notes in all of the photos before asking questions!

Step 1: Design

I had a list of features in mind when designing the chassis:

1) Have a very small footprint. The footprint of this design is 175mm x 187mm (6.88" x 7.36").

2) Use a full size ATX power supply. Small form factor (SFX) power supplies can get really expensive.

3) Everything must be easily accessible. Many PC chassis require motherboard removal to access the M.2 drive on the back of the motherboard.

4) Maximum airflow. A lot of mini ITX cases really limit airflow, with a subsequent rise in temps (especially with more powerful processors.)

5) Simple cable routing.

6) A carrying handle for easy portability.

7) Support a full height (2.75) graphics card.

8) 5.5" wide slot under the graphics card allows for installation of additional USB ports.

I looked at a few open style ITX chassis available but they were expensive, had limited airflow (due to distance between power supply and graphics card) or the M.2 drive on the back of the motherboard was inaccessible. I also wanted this to be able to be easy to modify. You want to use an ASUS ROG Crosshair VIII Impact mini DTX motherboard? No problem! Just make it 30mm taller. Want to use a SFX power supply? Easy- just use an adapter plate or change the design of the power supply plate (and make the whole chassis an inch shorter.) Since the motherboard plate and the power supply plate are separate you can modify one or the other without redesigning or rebuilding the whole chassis. You could even enlarge it and make an mATX version to use with a full length graphics card.

I also wanted this to be super easy to manufacture and be able to ship flat to reduce packaging required- SendCutSend to the rescue! SendCutSend takes your vector artwork and then laser cuts your design in various metal alloys and ships it to you within a matter of days! This was so easy to do it was silly.

First thing I did was lay out my components on cardboard and make measurements for cutouts and necessary clearances. Next the motherboard plate and power supply plate were drawn up using Inkscape. SendCutSend uses .eps files to laser cut so you need to use a drawing program like Inkscape or Illustrator to draw your design. Once I had my design done I printed it out full size to double check my dimensions.

Next I exported my Inkscape design as an .svg file and imported it into Fusion360 and converted it from a mesh model into a solid model. Then I placed models of components on the chassis model to make sure I liked the way everything looked. Grabcad is an excellent resource of 3d models for various components. It didn't matter that the component models weren't exact- I was just trying to get an idea as to what the final appearance would be.

When I was finished I sent my Inkscape .eps files to SendCutSend to cut the chassis parts from .375" thick 5052 Aluminum.

The Inkscape .eps files and .svg files are included here for you to use and modify! The .svg files are what you want to open in Inkscape to make modifications.

4/14/20- Update!

I have added a new power supply plate design named "PowersupplyplateV2" that changes how the graphics card mounts- the securing screw now sits on the opposite side compared to before. This allows you to insert the graphics card without having to remove the power supply plate first. It also has a larger rectangular slot that allows you to make a flat plate to hold the power switch vs. having to try and drill a 16mm hole through the .375" thick material. It also gives more room for additional USB ports (which I will be adding soon, along with some new 3d printed parts.) The other change was making the plate .375" longer so now it overlaps and matches up with the edge of the motherboard plate. This allows you to bolt it into the edge of the motherboard plate as well as the baseplate, making the entire assembly more rigid.

LOHTEC on YouTube has modified this design and created a smaller 3d printed version that uses a SFX power supply. Check it out here- https://cults3d.com/en/3d-model/gadget/10-8l-mini-itx-open-frame-sff-pc-case

Step 2: Frame Assembly

A few days later the laser cut Aluminum chassis frame arrived and it was time for assembly!

One of the limitations of laser cutting metal is that you cannot have shapes or cutouts smaller than 1x – 1.5x material thickness. Since the material is .375" thick this means that you must drill/tap all mounting holes.

I printed out hole templates for the ATX power supply and ITX motherboard (just do a google search for templates- I found some nice motherboard templates in this thread.) Then I taped them in place on the Aluminum parts and marked the holes using a center punch. I also marked holes for the bolts that hold the motherboard plate and power supply plate to the base plate. Then all through holes were drilled and I also drilled a countersink for all of the bolt heads for a nice clean look. All of the screws are 6-32 thread.

The motherboard is held using .375" long threaded standoffs so those holes were drilled and tapped for a 6-32 thread and the standoffs were screwed in place.

At this time I also drilled and tapped holes for the 2.5" SSD mount on the back side of the motherboard plate.

A 16mm diameter hole was then drilled for the power switch on the power supply plate.

Step 3: 3d Printed Accessories

Since I have a 3d printer I thought I'd make a few accessories to make the finished design a bit nicer.

First I made a hard drive mount for the 2.5" SSD. This was done using Tinkercad and it was incredibly easy to do! I basically made a block, hollowed out a section, made recessed mounting holes and holes to hold the hard drive, and then removed a bit of material in the base to reduce the print time. This was printed in PLA with 20% infill.

Next I thought I would make some cable combs as I had anticipated doing all custom sheathed cables (I later changed my mind- more on this later.) These were also designed in Tinkercad by combining larger cylinders and then putting holes in the center of each cylinder to create the cable guides. Super simple! I made cable combs for both 8 strand and 24 strand 4mm diameter sheathed cables. These were printed in PLA with 100% infill.

I didn't like seeing the back of the power switch so I also made a cover for that. It's basically a two cylinders and a cone hollowed out. This was printed in PLA with 100% infill.

All of the model files are here for you to use and modify as you see fit.

Step 4: Assembly

Final assembly!

First I installed the power supply. This fits so the fan draws air from underneath. Note that the power supply has .5" clearance on one side for cable routing.

Next was the motherboard, which is mounted to the standoffs using four 6-32 screws. You can see the second M.2 hard drive on the back side of the motherboard through the cutout in the Aluminum plate. This way it not only cools better but it's super easy to install and remove. The other M.2 hard drive is mounted under the heatsink on the front of the motherboard. The SSD mount is then screwed down on the back side of the motherboard plate.

Now comes the graphics card. This is the only part that is a bit tricky when you first install it as you need to install the securing screw for the card. You need to remove the power supply plate in order to install the graphics card and mark the location for the threaded hole for a 6-32 screw to secure the graphics card. This is done by removing the three bolts that secure the power supply mounting plate to the base plate, then moving the plate enough to slide the graphics card into place. Then tighten the mounting bolts and note the location of the graphics card mounting screw. Now disassemble everything on the power supply mounting plate and remove the plate from the rest of the chassis. Then drill and tap a hole for a 6-32 threaded screw where you marked it. This may require a long jobber type drill bit. It is very important to get this part right- go slow and take your time.

Once you have the completed drilling and tapping the hole for the graphics card screw you can reassemble everything. Now install the power switch, 2.5" SSD, and the processor cooler.

Step 5: Finish Wiring

Time to wire it up!

Originally I thought I would do all custom sheathed cabling as I anticipated having to run custom length cables. As it turns out the stock length cables that came with my ATX power supply were perfect!

All I had to do was connect the motherboard 24 pin cable, motherboard CPU power cable, 8 pin power cable for the graphics card, and SATA cables for the 2.5" SSD. That's it! The real beauty of an open chassis like this is how easy it is to run cables. :)

Now I have my mini desktop PC and it works beautifully. As with any project there is room for improvement so any and all suggestions are welcome! One idea I had while designing this is to make a simple folded sheet enclosure for people who would rather not see all of the guts. SendCutSend has a neat feature where you can cut a predefined "wave cut" pattern wherever you want a folded edge. Doing this you could easily make a folded Aluminum sheet slip on style cover that attached to the edges of the chassis frame using standoffs. This would allow you to make a custom cover with whatever design or pattern you want cut into it for air ventilation. Since this is made from Aluminum you can even anodize the chassis a vibrant color!

If you are using PCIE 4.0 NVME drives you could also mount a fan to the back side of the motherboard plate to cool the drive. You could even use that area to mount a liquid cooling setup if you'd rather build a liquid cooled rig instead of an air cooled setup.

If you build this be sure to post pictures and if you have any questions be sure to let me know!