CPU air cooler runs ice-cold water through its heatpipes to liquid-cool a GPU — negative-temp DIY mod sees up to 17% performance uplift
We're back with another classic from TrashBench, the ingenious modder who has previously dunked GPUs into transmission fluid to cool them. Perhaps that's not very convenient, so why not try something far more feasible and, maybe even genuinely practical? Taking an air cooler, dismantling it, and turning it into a Frankenstein AIO that can tame GPUs like it's a walk in the park.
Our journey starts with a Thermalright Peerless Assassin, a competent cooler on its own, but clearly, there's room for improvement. One by one, the fins from its heatsink are removed until the heatpipes running through the finstack are exposed just enough. Then, a disc cutter is carefully run through the top to get access to the magic sauce.
For those unaware, the heatpipes inside an air cooler are hollow, with a small amount of liquid inside that evaporates and condenses during heat cycles, acting as a phase-change system. That's enough to cool a CPU when combined with fans on either side. So, when we cut the tops off the pipes, we see channels inside leading directly to the base plate, which enables this madness.


Thin water tubes are connected and secured to these pipes, and once initial leaks are fixed, a pump at the other end successfully injects green-colored water through them, bringing this custom apparatus to life. It's time for testing, and an MSI RTX 3070 is the first recipient of this honor.
After being stripped down to expose the die, the DIY cooler is retrofitted on top with surprising conviction, and the whole thing is put on a test bench. On the side is a portable ice chiller, on which a 12V diaphragm pump is mounted to power the entire setup. Once turned on, ice-cold water flows through the heat pipes, touching the 3070's GPU, which sits at a casual -14 degrees Celsius.
Owing to his name, TrashBench runs a bunch of games and benchmarks on this new below-zero RTX 3070, and compared to the stock results, we see an average 10% uplift across the board. The unlocked cooling headroom enables a +320 MHz overclock that delivers decent improvements, but it's not drastic.
This is where the GTX 960 comes in.
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The same story follows: the graphics card is disassembled, and its stock cooler/shroud is replaced with our mighty water-injected cooler. But the results here are far more impressive; Cyberpunk 2077 shows a massive 21% increase in FPS, while COD: Black Ops 7 demonstrates a 220 MHz uplift in boost clocks. Overall, across all tests, the GTX 960 saw a ~17% performance bump.



TrashBench doesn't declare the experiment a success or a failure at the end. Still, we're pretty confident in singing its praises — this seems like a legit upgrade to an existing air cooler, turning it into a pseudo AIO that can help overclock GPUs without requiring a full-blown liquid nitrogen setup. It's wild but just accessible enough to be something truly special, adding the "fun" in functional.
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Hassam Nasir is a die-hard hardware enthusiast with years of experience as a tech editor and writer, focusing on detailed CPU comparisons and general hardware news. When he’s not working, you’ll find him bending tubes for his ever-evolving custom water-loop gaming rig or benchmarking the latest CPUs and GPUs just for fun.