A YouTuber by the name of SURGE⚡️ posted a video back on July 6th 2025 upgrading a 2018 Mac mini to an 9-core i9 CPU.
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The Intel chip appears to be an I9-9980HK, the same which is used in the 2019 16″ 2.4 GHz i9 MacBook Pro.
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(Above: MAC MINI 2018 i9 CPU UPGRADE!! THE MAC MINI THAT APPLE NEVER MADE!!!! – URL)
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Removing the old CPU

He starts the video by saying it was a chip from an A2141 donor board, a 2019 16″ MacBook Pro. The video features sped up clips of disassembly and assembly, and he also shares thoughts along the way.
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The CPU and RAM slots are very close in proximity, and this poses a problem since the RAM slots are made of plastic. SURGE⚡️ needed to find a way to protect the RAM slots while replacing the CPU, so he layered on some Kapton tape and a couple small shields from an iPad board. Since the board absorbs such a huge amount of heat, a preheater is needed.
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Reballing the i9

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The finished product

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In conclusion

Surely this mini has the ill-fated Apple T2 chip, but it seems like the CPU can be upgraded without any issues, breathing even more life into the very last of the Intel Mac minis. It may be 2025 and perhaps 8-core chips have become more ubiquitous, but it doesn’t make it any less astounding this was even possible. This is certainly one way to maximize a 2018 mini into space.. and beyond!