Good afternoon/morning. I built my PC nearly 2 years ago now and I've not had any troubles up to this point, however the last couple times I've started it up from cold the CPU temp idles at around 95°C on HW monitor; despite throttling down to 500MHz, hearing the pump going full blast and feeling the air from the fan being cold, if I do anything it still climbs to 110+ before shutting off, I start back up into the BIOS where it confirms the ballpark of the HW monitor reading, then 30 seconds into Windows the temperature drops dramatically to what it's always been at idle ~25-30°C, then the pump backs off and the clocks are what they should be. Is this going to be a case of old thermal paste and needing to replace it? Or is there possibly a bad temp sensor?
Specs:
Ryzen 5 2600
Cooler Master ML120L AIO
GTX 1080
Gigabyte 450M DS3H