How I made a custom PC case as a Mechanical Engineer

I wanted a PC that was compact, portable, robust, and simply… different. The best and least cost-effective way to do this is by creating my own custom case.

Figure 1: Final Custom PC Case by Paul Lee

Introduction

I’m a mechanical engineer by degree from the University of Texas at Austin. When designing this case, I really should have ran heat and flow simulations to validate the cooling performance of the case. Without access to proper simulation softwares, I shifted my main focus in mechanical design to achieve compactness, portability, and durability while slapping on as many fans as I could. Hope you enjoy my journey.

PC Specifications

As my second PC build, I wanted an upgrade from my 2017 budget build. I sought high-end specs, albeit not the highest. Below are the final specifications for my new build and reasons why I chose those components.

Figure 2: PC Part Picker

CPU — Intel Core i7–9700K 3.6 GHz 8-Core Processor

You may wonder: Why Intel? Why an i7? Why the 9th gen? It was simply on sale for $199.99 at Microcenter. This processor normally retails for $300–350. The value of processing power to dollar cost was just too good for me to pass up.

CPU Cooler — Noctua NH-D15 Chromax.Black

You may also wonder: Why not liquid cooled? Why Noctua? Well this decision refers back to the overall goal for my PC build: Portability. I had concerns with AIO liquid coolers during transport. Although AIO coolers are pretty unlikely to fail, the risk & severity is too high if it did (ex. leaking). Another consideration was if I were to take my PC on a flight, there may be TSA complications with the liquid. The downside to a heatsink & fan cooler is size. Now this hurts the portability metric, but the risks of AIO coolers outweighed the more traditional cooler.

Motherboard — Gigabyte Z390 I Aorus Pro Wifi Mini ITX

Since I aimed to create a mini PC, I had to find a mini ITX motherboard. My selections were very narrow as a lot of manufacturers stopped making ITX boards with my older gen CPU socket. I actually felt extremely lucky to get my hands on this board and definitely paid a premium from retail prices. Nonetheless, this was one of the top boards I sought for. It features WiFi, Bluetooth, M.2 NVME storage, and a ton of I/O ports given its small size.

GPU — Nvidia GeForce RTX 3080 FE

I feel so fortunate to be able to get my grubby little hands on this card. Out of all the 30 series cards, the Founder’s Edition was the most aesthetically pleasing to me. If you want to know how I got it, I wrote a Medium article here. I chose the 3080 since it offered the most performance per dollar.

PSU — SeaSonic Focus 750W 80+ Gold Fully Modular

According to brief literature review, 750W was the minimum wattage suggested based on my specs (CPU, Mobo, GPU). I went with an ATX PSU because the small form factor PSU’s were just way more expensive than what it’d be worth.

Memory — G.Skill Ripjaws V Series 1x16GB DDR4–3200

I went with 1x16GB stick to have the option of upgrading my memory to 32GB. DDR4–3200 was around the spec I was looking for and the G.Skill was just the cheapest option for me.

Storage — Crucial P1 1TB M.2 NVME

Just looked for the cheapest 1TB M.2 NVME SSD. I have two M.2 slots on my motherboard, but I’ll only install one for now.

3D CAD Model SolidWorks

Now that all the PC specs are chosen, the next step was to create a design around them. I created several models in order to find the most compact and efficient use of space. I used SolidWorks to model all of the PC components. The final CAD (computer-aided design) model is shown in Figure 3.

Figure 3: Final CAD Model of the PC

(NOTE: In the final assembly of the PC, the GPU is flipped as opposed to the CAD model)

I envisioned a tower case that relied heavily on T-slot aluminum extrusions. As an engineer, you already know how versatile these framings are. They provide flexibility, customizability, and durability. The only downside to these is that they’re not exactly cheap. When creating this design, I did my best to minimize the amount of struts I’ll need.

The whole PC will be encased by acrylic side panels. Acrylic is strong, impact resistant, temperature resistant, and easily modifiable while being extremely transparent. Having side panels should also help reduce dust & particulate accumulation in the PC versus and open-case design.

In terms of air flow, the main intake will be induced by two fans on the sides of the PC. The PC is also raised by rubber feet allowing intake from the bottom (PSU intake is from the bottom). The CPU cooler fans are directed upward and the main exhaust will be through the top of the PC. The GPU is also exhausts outward. More discussion about thermal performance will be explored in a later section.

Physical Build

The CAD model was extremely useful for detailing a list of hardware I’ll need for the case. I installed an LED strip to the front of my PC. I’m not a huge fan of rainbow RGB, so I have the light encoded to white.

Figure 4: PC illuminating my apartment living room

Custom Extrusions (Framing)

My design relied heavily on the ability to procure a set of custom length aluminum extrusions. Fortunately, these are commercially available at 80/20 Inc. An anodized black coating is an additional option. After a 4 week lead time the extrusions were at my doorstep. The quality of the delivered product is phenomenal, as shown in Figure 5.

Figure 5: 8020 Custom-length Aluminum Extrusions Anodized Black

Laser Cutting (Side panels)

The acrylic side panels were laser cut at UT Austin’s Inventionworks center using a Full Spectrum Pro-Series laser cutter. 2D images were rendered from my CAD model, and converted into a vectorized file that could be understood by the laser cutter.

Figure 6: UT Austin Inventionworks Laser Cutter

Soldering (Power button)

One of the conveniences of manufactured PC cases are the front IO options. Unfortunately that means I have to integrate my own front IO, including the power button. I bought a momentary push button from Adafruit and soldered jumper wires that can be plugged directly into the motherboard.

Figure 7: Soldering Wires on Momentary Push Button

Assembly

A detailed list of hardware can be seen in the bill of materials section. With all the components on hand, now it comes down to the assembly. The whole assembly probably took over 5 hours. I underestimated the amount of hardware (screws, brackets, etc.) I needed. I probably spent 40% of the assembly time with a screwdriver in my hand.

Figure 8: PC Case Skeletal Frame

The first step was creating the skeletal frame. The overall structure is centered around the stability of the frame attachments. The screws were not thread locked, but were tightly torqued. At this stage, main components can be retrofitted for the first time, as seen in Figure 8.

The motherboard is attached to the back acrylic panel of the case. The motherboard is lifted with hex standoffs to to be clear of any extrusions underneath it. I was very conscious about structural integrity and added support to minimize flexing in the acrylic panel. Extrusions underneath the motherboard were insulated with electrical tape to avoid shorting. The motherboard is held up very sturdily despite having such a large CPU cooler, as shown in Figure 9.

Figure 9: Mounting Motherboard onto PC Case

Without getting into too much detail, The GPU was secured by pressure fitting some rubber feet extended by screws. This held the GPU in place surprisingly well, but there’s also not a lot of room for it to wiggle. Chest handles were directly mounted onto the aluminum extrusions on the front and top of the PC. Having a spring loaded handle is extremely handy during transport.

Figure 10: Completed Assembly

Assembly Challenges

You know what they say, “nothing is ever easy.” The biggest oversight in mechanical design is missing foresight in the assembly process. For example, placing a screw that’s inaccessible by a screwdriver. To my surprise, I only had one major design flaw that almost ended up working in my favor.

Originally, I had the 3080 facing inward, where air intake would be from the outside and exhaust would be into the PC (now that I’m looking back, this would be horrible because then I’d be baking all the other components in my PC). The problem with the original orientation was that the PCI express slot conflicted with the bulkiness of the riser cable. Instead, I was forced to flip the GPU to where the exhaust is facing outward. Unfortunately, the top panel cutout was not made symmetrically, so I did have to get a hack saw and manually create additional cutouts.

Completed Build — Size Comparison

As a mini ITX PC build, there has to be comparison pictures. In Figure 11, a standard-sized paper towel is used as a reference. The overall dimensions of the PC is about 9in x 9in x 12in. Not the smallest PC build out there, but also not that much bigger than a paper towel.

Figure 11: Size Comparison to a Standard Paper Towel

The other comparison was in reference to an ATX build, as seen in Figure 12. A Fractal Meshify 2 is on the left and my custom build is on the right. In terms of width, the two PCs are comparable, but the Fractal is much taller and much longer.

Figure 12: Size Comparison to a Fractal Meshify 2 Case

Thermal Performance

The main skepticism about mini pc builds is thermal performance due to lack of airflow. A good way to confirm good heat transfer and air flow is by running a computational fluid dynamics (CFD) simulation. Unfortunately, I don’t have access to such software and didn’t put in much effort in learning open-sourced CFD programs. I primarily used my engineering intuition and placed as many fans as I could. Maybe in a future post, I’ll have a CFD simulation of my PC.

Simulations are good checks during the design phase of the PC build. However, since my PC is already complete, the best way to check for thermal performance is simply just measuring temperatures under various loads.

CPU Thermal Performance [i7 9700K]

The CPU cooler installed is the Noctua NH-D15 Chromax.black, arguably one of the best heatsink and fan coolers on the market. This cooler features a dual-tower heatsink design and 2x NF-A15 PWM fans. This cooler is considered to rival the performance of all-in-one water coolers.

According to online recommendations, AIDA64 is considered one of the highly regarded CPU stress testers. AIDA64 supposedly “takes a more practical approach by mimicking real-world processes that place a 100% load on the processor” [Source 1].

As shown in Figure 13 below, the stress test ran for about 20mins and the main CPU temperature held steady around 60C, while the CPU cores got to about 70C.

Figure 13: CPU Stress Test — AIDA64

GPU Thermal Performance [RTX 3080 FE]

The thermal performance of my GPU is mostly limited by the manufacturer’s (Nvidia’s) cooling design. There’s not much I can do to improve its cooling performance other than feed the intake with dry cold air. Anyways, I wasn’t too concerned either since I won’t be overclocking it or operating even close to its performance boundary.

In Figure 14 below, my GPU only reached a peak temperature of about 60C while running at full capacity and max fan speed after crypto-mining for over 6 hours. I know this isn’t the even close to good metric for stress testing, but this is probably as hard as I’ll run it in my use-case.

Figure 14: GPU Stress Test: Cryptomining

Bill of Materials

You must all be dying to know how much I spent on this project. It wasn’t cheap. I had to keep reminding myself that I’m paying premiums for the learning experience. The detailed bill of materials is shown in Figure 15.

Figure 15: Final Bill of Materials

The outstanding cost for all the PC parts (without case) came out to be $1,466 pre-tax (or $1,587 post-tax).

The cost of just all the hardware for the PC case came out to be $327 pre-tax (or $354 post-tax). Now it’s important to know that I did not prorate the costs of hardware that had to be bought in bulk. Manufactured cases are cheaper since the cost is just of the materials used. A one-time build will be significantly more expensive.

The total cost of the whole PC came out to be $1,793 pre-tax (or $1,941 post-tax). Overall, this was within my expectations of budgeting for a $2,000 PC.

Conclusion

Figure 16: Should I make a YouTube video?

Thank you so much for following me on my PC building journey. This was definitely a first-time thing, and I’m glad I had the opportunity to document it. If there’s more information you’d like to know, let me know in the comments section! I made a really cool one-of-a-kind PC that I hope can inspire others.

If you enjoyed content like this, please let me know by clapping, commenting, or consider following! I have many more projects and ideas to come soon. Also feel free to send a LinkedIn request, I’d love to stay network and stay connected.

Mechanical Engineer — University of Texas at Austin #2018

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