For many years, I have wanted to create a PC submerged in mineral oil, but I didn’t do this because it isn’t easy. Though mineral oil isn’t expensive (roughly $2/pint) it adds up when you need gallons of it. Aquariums also aren’t exactly designed with PC hardware in mind, where positioning the hardware properly is a challenge. So, I needed the smallest aquarium possible to prevent the PC hardware from shifting around, and to reduce the amount of oil needed. However, a lower volume means a lower thermal capacity. This means I also need PC hardware that isn’t too demanding. The last challenge was finding an aquarium to fit my hardware. This proved to be difficult, so I had to resort to building my own.
As of June of 2017, I felt ready to start this project. I had cash to spare, a 60W (maximum output) server with no dedicated chassis, and a bunch of tools I’ve collected over the years. My shopping list involved a large sheet of acrylic, super glue, silicone glue, a steel cupboard knob, cupboard hinges, aluminum L brackets, and a bunch of mineral oil. Here’s how the build process went:
The tank was originally intended to support a full size ATX PSU, where it would sit beside the CPU heatsink. This resulted in a 7x7x9 inch box. I outlined each of the starting cuts on the film protecting the acrylic. Two of the panels were then cut into 7×7 squares for the left and right walls.
In hindsight, I would have rather had two 9×9 and two 7×9. This would have allowed for more headroom between the lid and the I/O ports of the motherboard. It’d also have reduced the amount of cutting needed.
After the sanding was done, I removed the protective film and washed away dust.
Next came gluing the panels together via the silicone gel. I found the easiest way to do this was to take a 9 inch tall box and other random objects lying around to keep the panels aligned and straight.
The lid was fairly easy to set up. It just needed some screw holes for the hinges and the door knob.
Here is an early stage of the lid attached with the knob. The square cut-out on the right side of the tank is intended for cables to run through. I’d have liked it to have been a little smaller, but the size was to compensate for a crack during the cutting process.
Next came creating the aluminum trimmings. I originally intended to create trims around each of the corners of the tank, not just to make it look nice but for better structural integrity. I decided against this for various reasons, but the main ones being cost and imperfect measurements. With proper tools, I likely would have done trimming all around, but instead I just stuck with the lid.
The trimming was applied to the lid via super glue. The panel for the lid had a lot of material loss due to the sanding, so the trimming helped hide this problem.
Now I had to test if everything would fit. The hard drives must be kept from being submerged, so I had them sit on top of the PSU, where the oil won’t reach. Everything seem to fit perfectly.
Unfortunately, the PSU fan was moving uselessly slow and the wall bubbler I had was causing foaming problems, among other things. It was time to make adjustments.
I bought this 90W Pico PSU for $16 on eBay. Despite being an outdated model, it still fit my needs perfectly. It is only a 20-pin connector, but this PC isn’t demanding enough to need the extra +4. The PC runs perfectly stable without it.
Another benefit to this PSU is how it allows me to quickly and easily unplug the PC from the wall, where the old setup had the power cord submerged.
After making the adjustments, it was time to add the mineral oil. Here are just some of the bottles I collected after multiple visits to stores like Walmart and Target.
Here’s the complete build. Due to the lack of height, I had to cut a hole for the I/O panel in the lid, and as a result, the knob had to come off with it. I added some foam padding along the rim to prevent dust from slipping in the tank.
I also modified the HDD tray so it could securely hang over the oil. A little ugly, but it works.
At last minute, I added some LED strips under the lid trimming. The LEDs are connected to the CPU fan connector, and change in brightness based on temperature. Through a shell script, I can also quickly turn them off or set to full brightness.
Below are some larger images of the final results. Thanks to Sam Desmond for supplying the decorations. Here’s a video of the bubbler in action too, including the noise it makes…
After a full night of being on, the hottest sensor reading seems to be in the upper 40s (Celsius) but the temperature steadily climbs after several hours, where even the walls feel slightly warm.
Having no formal training and poor craftsmanship, I learned a lot from this, but there is a lot I could have and would have done different or better such as:
- Design this with the Pico PSU in mind from the very beginning. But, at least planning around an ATX PSU gave me room for decorations.
- Make the aquarium taller by a couple inches. I wouldn’t have to add more fluid, but it would’ve made the lid situation easier, and I could’ve used the extra few inches I cut off the acrylic (which in turn would mean less cutting and less sanding).
- Use something more accurate and stable for cutting, like a band saw, or at least a sanding belt. Reciprocating saws get the job done but they sure are crude.
- Take a different approach to the bubbler. Other mineral oil PCs don’t have the foaming issue I had. I suppose this would have been trial and error, though.
- Use a different pump entirely. The one I have now can get pretty noisy and hot sometimes, and I wanted to power it via the PSU (fewer cables to deal with, and it could have otherwise been automated).
- Avoid using the razor blade on the acrylic itself.