100W car amplifier hacked into a custom RTX 3080 heatsink — custom mod slashes GPU temps by 10°C and looks absolutely stunning

A Redditor, ComplexSupermarket89, modified their old MSI RTX 3080 Ventus, which used to rank among the best graphics cards, after its maximum memory and hotspot temperatures started hitting 102 and 105 degrees Celsius, respectively. The DIYer repurposed a car amplifier as a heatsink for the RTX 3080.

According to the user, they initially repadded their graphics card to solve the overheating issue, but it happened again within a year. So, they decided to mod the GPU this time by adding Arctic MX-7 thermal paste between the memory chips, using better thermal pads, and replacing the MSI Ventus backplate with a heatsink.

When they rummaged through their stack of aluminum scrap, they found a 100-watt car amplifier with its massive heatsink. They cut this down to size to fit the GPU, covered potential short points with polyimide tape, and then mounted the aluminum block where the backplate used to go. They initially sanded the original black powder-coated heatsink to achieve a silver finish. Unfortunately, they can’t clean it up thoroughly, so they decided to paint it with white high-temperature engine enamel, giving the graphics card a white finish.

Aside from the massive new heatsink, they also built a custom fascia and a lower fan shroud from scrap aluminum, and replaced the stock fans with three 92mm Thermalright RGB fans. The front part of the fan shroud is mounted on the original mounts on the GPU’s stock heatsink, but they also added a couple of zip ties for support. As for the rear of the shroud, it’s held by two steel brackets mounted to the custom heatsink, practically sandwiching the GPU with aluminum.

My new "custom" RTX 3080, made entirely from scraps, with only hand tools from r/pcmasterrace

All this resulted in lower GPU temperatures, with the hotspots dropping by at least 20 degrees Celsius. The memory chips still reach 96 to 98 degrees Celsius, but the large chunk of aluminum means it takes much longer to get those temperatures. Still, ComplexSupermarket89 isn’t satisfied with this, and they’re considering carving out a circular section on the custom heatsink to mount a recessed fan for additional cooling.

The added aluminum is estimated to weigh over 3 pounds, so they also added a 90-degree steel bracket to support the GPU and prevent damage to the PCIe card slot or the motherboard. Thankfully, it seems to be effective, with the graphics card not sagging even after three days post-install.

ComplexSupermarket89 said the mod is a bit silly, especially since the RTX 30-series is pretty old by now. They even said they probably won’t keep the GPU much longer and will upgrade to the next AMD flagship when it becomes available. Still, they say it's a “passion project, a labor of love,” and we can see it in the results. If you're on the market for a new graphics card, our GPU 2026 pricing tracker can be useful.

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