@condret @BowsacNoodle @ooignignoktoo impossible to check thermal paste right now, the cooler was said to be "compatible" but it was such a tight fit that I'm not sure I'll ever be able to yank it out

No bloated caps either

CPU temps looks totally normal too
sensors
coretemp-isa-0000
Adapter: ISA adapter
Package id 0: +40.0°C (high = +84.0°C, crit = +100.0°C)
Core 0: +33.0°C (high = +84.0°C, crit = +100.0°C)
Core 1: +35.0°C (high = +84.0°C, crit = +100.0°C)
Core 2: +32.0°C (high = +84.0°C, crit = +100.0°C)
Core 3: +32.0°C (high = +84.0°C, crit = +100.0°C)

acpitz-acpi-0
Adapter: ACPI interface
temp1: +27.8°C (crit = +119.0°C)
temp2: +29.8°C (crit = +119.0°C)

pch_skylake-virtual-0
Adapter: Virtual device
temp1: +52.0°C

I figured it could have been the bluetooth adapters, but even with them remove and a proper keyboard and mouse connected behind, it still does it

It does it on the New AND old Mx Linux install, there's no reasons why it would do it on the old. And while Windows isn't as affected, there does seem to be mouse stutter on that side too somehow