Why oil-cooled PCs aren’t popular anymore
At some point, PC performance enthusiasts came up with the idea of cooling a computer by soaking its components in mineral oil — and it worked! But today nobody does it anymore, so what happened to these awesome submerged “fish tank” PCs?
How does this even work?
To make a computer cooled by mineral oil, you need a few things on your shopping list:
A leak-proof container, such as an aquarium tank. Special non-conductive mineral oil. An (optional) pump that circulates oil in the system. An (optional) radiator, although you’ll want one on a system that’s always on.
All solid components of the computer are immersed in mineral oil and their heat is dissipated directly into it. Mineral oil has a high specific heat capacity. That’s how much energy you have to pump into the oil to raise the temperature by one degree.
In practice, this means that you can continue to heat the oil and heat it up slowly until it reaches temperature equilibrium. From that moment on, the system will run at a stable temperature under load. Assuming this temperature is below the maximum range, your cooling concerns are over.
Passive oil cooling is useful for people who use their computer for a few hours a day and then turn it off, put it to sleep, or leave it overnight. The oil cools slowly, ready to absorb more heat the next day.
For systems that require active cooling, you can use a pump that circulates the oil through a radiator. Fans extract heat from the oil flowing through the radiator and cool it down. While not as quiet as a passive system, using large, low-speed fans that only activate at certain temperature thresholds is still quite inaudible.
Early homemade experiments
As with water cooling, in the beginning you couldn’t buy the equipment you needed to make a mineral oil system off the shelf. That meant that people who wanted to try to build such a computer would have to visit the local aquarium store and perhaps reuse small oil radiators for cars.
You can still find forum posts on the internet about these projects. Likewise, some magazine publications and YouTubers tried to build these systems as well, with varying degrees of success. Interest in oil-cooled PCs started to soar among performance enthusiasts. “Takeoff” may be an exaggeration, but it was an intriguing option if you wanted high-performance cooling in a system that could run 24/7.
Commercial Mineral Oil Kits
With enough interest in the enthusiast market, there were actually some commercial mineral oil kits for sale. The best known of these is the custom system builder kit puget† The company tested and developed several iterations of a mineral oil cooling system, running their first prototype for over a year to see the long-term effects. Satisfied that it was feasible, you could buy the kit (for a while) from them.
Unfortunately, another company claimed that Puget’s oil cooling kit infringed on their patents, and instead of paying royalties, Puget decided to stop selling the kits. It is not clear how many people have bought such kits and whether they have built long-term systems with them. Anyway, we couldn’t find many commercial kits on the internet today. One company, Coolbitts, does offer a immersion kit for high-end systems for a dazzling $2450.
Mineral oil cooling has problems
Cooling a computer with mineral oil has many benefits and it is an interesting way to create a unique computer that looks great. At least, assuming you do it right. That said, there are many issues you will face when building a mineral oil computer system.
First, the oil itself must be maintained. Puget systems said during their testing that it would probably be enough to change or filter the oil once a year. It’s not that the oil gets worse as it cools, it’s just that it becomes less clear over time, which affects the look of the computer.
If you have optical or mechanical hard drives, they cannot be submerged in oil as they are designed to operate in air. This means that you have to create a special bay and cabling. These days, with SSDs and digital downloads, you don’t need these types of drives on your PC anymore, so it’s less of an issue.
Any input/output device, such as USB ports, should preferably be out of the oil. While it won’t harm your ports or your plugs in the short term, having a non-conductive liquid between the two connectors probably isn’t a good idea. Oil can also suck up connected cables and slowly spill out of the tank!
There are also stories of mineral oil dissolving rubber components. When Puget tested his system, even after a year, there was no evidence at all. However, it does depend on the exact oil and type of material. That is why it is important to specialized mineral oil and not just the stuff you find in a supermarket.
Ultimately, mineral oil PC cooling has many maintenance issues that make it impractical for general use, which is probably why water cooling has become the preferred way to cool high-performance components.
Water cooling takes the cake
Nowadays it is not difficult to cool your CPU water. You can just buy a water cooler from a store, attach it to the rails that are probably already in your PC case, and stick it to your CPU just as easily as a normal air cooler. GPUs are trickier, but if you buy the right model, you can find a water cooler for it or just buy a card that’s water-cooled out of the box.
Custom water cooling loops remain a niche solution, but it’s not hard to find professional system builders who will build a custom cooling loop system for you. The maintenance of sealed all-in-one coolers is non-existent as they are not designed to be refilled or opened. Maintenance on custom loops represents an hour or two of work, depending on the exact design. This maintenance only needs to be done every few months or every few years, depending on the specific coolant. So it’s not hard to see why water cooling is (relatively) mainstream these days, but mineral oil aquarium PCs are not.
Oil cooling is still there!
That doesn’t mean oil-cooled PCs are gone altogether. You will still find that people still make them, even in 2021† Is it something you should keep in mind? Probably not, but it looks like a fascinating project to tackle and in some cases, such as needing a completely silent passively cooled system, there may even be a practical reason to try it.