A PC That Uses Hot Coffee As Coolant

Modern computers generate a great deal of heat when under load, thus we cool them with fans and sometimes even water cooling systems. [Doug MacDowell] figured that water was alright, but why not use coffee instead?

Someone tell us how [Doug] made this graph look like it’s right out of a 1970s college textbook.
The concept is simple enough — replace water in a PC’s cooling loop with fresh-brewed coffee. [Doug] fully integrated an entire PC build on to the side of a General Electric drip coffee maker. It’s an absolute mess of tubes and wires, but it’s both a PC and a functional coffee maker in one.

The coffee maker percolates coffee as per normal into the carafe, and from there, it’s then pumped through two radiators on top of the PC. From there, it circulates to the water block on top of the CPU, and then back to the carafe on the coffee maker where the cycle repeats. Doug notes the coffee is initially so hot (90 C) that the PC is at risk of crashing, but after 75 minutes circulating through the system, the coffee and CPU sit at an equilibrium temperature of 33 C.

You can’t really drink coffee from this machine. PC water cooling components are not food safe in any way, and [Doug] notes mold will become an issue over time. For short periods at least, though, it’s possible to sort-of-cool your computer with hot, fresh coffee if you really want to do that.

We’ve featured some great hacks of conventional coffee machines over the years, including this fantastic talk at Supercon 2023.

38 thoughts on “A PC That Uses Hot Coffee As Coolant

  1. “You can’t really drink coffee from this machine. PC water cooling components are not food safe in any way…”

    However, if you included a food-safe heat exchanger, you could drink the coffee. C’mon, folks, this stuff is both necessary and getting expensive, no need to waste good coffee.

  2. In case we needed another meme engineering project to deplete our planet’s ressources faster

    I get the appeal of building for building’s sake but at some point it becomes unethical

    1. It’s counterproductive to shame such a miniscule uses of energy. It gives the false impression that saving the environment requires giving up all joy.

      Transportation and climate control make up such a large fraction of our energy usage that talking about coffee makes is a distraction.

      If you drive alone in a car at some point this week then you’ve committed an environmental sin 100x larger.
      If you’ve flown on an airplane this year, it’s 1,000x.

      1. Meh.. needlessly adding to a problem is not something to be celebrated just as much as micro-managing solutions to macro problems. The idea that ‘if you drove a car .. ‘ etc is a false analogy right from the start as most people find transportation necessary where a project like this is necessary to no one.

        1. I guess we shall stop all activities that are not essential to the continuation of the human race? Because doing something fun for the sake of fun with spare resources that would have just been waste anyways is no longer allowed.

    2. Art is a waste of resources too!

      We should all live in Soviet blocks, wear uniforms and only think things pooh bear has written down for us to think!

      The biggest waste of resources?
      hipho’s life!
      I know an air thief when I hear his/her ‘thoughts’.
      Save the planet…yourself!

    1. Nah, the aluminum heat sinks react with the acids. After a week there will be a good thick layer of aluminum oxide. The aluminum deposited in your brain might be another matter.

      1. Struggling with brain fog this morning, but I was thinking something similar. A combination of heat pump(s?) and exchanger(s?) ought to be able to both cool a PC and heat water/tea/coffee. Maybe throw in some peltiers to power LEDs based on the heat delta, and you might be able to make the least efficient PC cooler/water warmer possible.

    1. Thanks PlotLover. It took a very long time. Here’s a quick breakdown:

      I plotted a grid in graphite and marked the data point. To create the lines in the graph I used a circle template for each data point (for consistent line width) then connected the edges of the circles with a ruler. I used ink on top of the graphite, and then used a vintage lettering kit (like the one @Dude shared in the link) to do the lettering.

      At the very end you use an eraser to remove all the graphite, and you’re left with the most satisfying clean ink line you can imagine :)

      I’ve done more hand drawn dataviz if you want to check them out: https://www.dougmacdowell.com/data-landscapes.html

      1. At the very end you use an eraser to remove all the graphite

        If you were doing a photo exposure process or a xerox copy, the lighter graphite lines would vanish automatically by blowing out the contrast. To make it more reliable, you’d use colored graphite pens, magenta or blue, which are easy to see by eye and easily filtered out in the developing process.

        1. Interesting techniques – thanks for sharing. Leaving some evidence of the graphite lines was on purpose (a clue that the graph was made by hand).

          Sounds like you might be a draftsman?

  3. As other commenters have mentioned, you could create a version of this that actually brews drinkable coffee using the computer itself. All you need to add is a food-safe heat exchanger (stainless-steel flat plate heat exchangers are a good option). Then allow the CPU to heat the cooling loop to its maximum thermal throttling temperature. You might have to tweak a bios setting or even carefully select a CPU for optimal coffee brewing temp – not all CPUs will be configured to reach the 90-95c that many brewing methods require.
    Also, if you want your coffee in a hurry, even the most power-hungry CPU is only going to be able to deliver a few hundred sustained watts, which is pretty disappointing. Unless you’re building a multi-processor coffee server, you’ll probably want to add a water-cooled GPU to the loop for rapid heating. Nvidia’s flagship models like the RTX 5090 and 4090 are excellent options as they can draw almost as much power as a standard coffeemaker, but the budget-conscious could build a nice, vintage-inspired multi-gpu system using, say, four GTX 1080s in order to achieve coffee SLI. AMD’s latest GPUs are also a viable option, while their decade-old RTX 480 series is very affordable and notoriously power hungry.

    (I have some relevant experience, believe it or not, as about ten years ago I built a water-cooled PC that could keep a hot tub at a nice soaking temperature. Never documented the build, but it worked remarkably well. Of course it used a heat exchanger to keep the hot tub water isolated from the PC.)

  4. There are better uses of coffee than cooling a CPU.

    On the other hand, when someone asks “does your computer run Java” you can say “Not only does it run Java, it runs ON Java!”

  5. I’m sorely disappointed that nobody has yet suggested running a nice hot cup of tea through this thing to create a finite improbability generator. Of course, you would also have to swap out the motherboard for the logic circuits of a Bambleweeny 57 Sub-Meson Brain connected to an atomic vector plotter, but I’m sure that would be a trivial upgrade.

    R.I.P. Douglas Adams

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