How old is your Corsair H100X ?
Yes, you need to do regular vacuums of the water Radiator - excess dust will definitely destroy cooling performance.
Sorry to state the obvious, but have you checked your Corsair iCue software to make sure the fan speed curves are set correctly, so that the speeds are fast enough when the CPU is under maximum load?
Make sure the Water Pump is running at full speed. Some people make the mistake of the water pump working like a fan, I running way too slow, which compromises the cooling.
I've had many problems with Corsair closed loop water coolers in the past. I may have just been unlucky, but I would never buy this brand ever again.
The problem component always ended up being the Water Pump.
The first one I bought (many years ago now), started making a bad ticking noise a few months after it was installed.
I got it replaced under warranty.... 3 years later it just died one day.
I've seen autopsies on YouTube were the water block is opened up (all brands of closed loop water coolers) and you can see all this debris (metal filings and gunk), which is slowing down movement of water through the loop.
I also experienced horrific problems with the
older Corsair software, that was causing my computer to turn on/off.
Long story short, when I built my new computer in 2020, I vowed to never use Corsair cooling ever again.
I also didn't want to have to use, bad software to control my water cooler.
After reading tonnes of reviews, I went with a BeQuiet 280mm water cooler.
www.bequiet.com/en/watercooler
BeQuiet cooling runs directly off the fan headers of your Motherboard.
You can control fan/pump speeds directly through BIOS settings
or do what I did
Control Fan speeds and Pump using Motherboard Fan Control software (I use ASUS AI Suite Fan Expert).
BeQuiet water cooler has been the best cooler I have ever used.
