Question i9 9900k cooling

Apr 22, 2019
I recently build a new system for gaming and a bit of handbrake encoding as follows:

PCPartPicker part list:

CPU: Intel - Core i9-9900K 3.6 GHz 8-Core Processor (£464.40 @ CCL Computers)
CPU Cooler: Corsair - H100i PRO 75 CFM Liquid CPU Cooler (£98.14 @ Amazon UK)
Motherboard: MSI - MPG Z390M GAMING EDGE AC Micro ATX LGA1151 Motherboard (£164.99 @ Amazon UK)
Memory: Corsair - Vengeance LPX 16 GB (2 x 8 GB) DDR4-3600 Memory (£168.46 @ Amazon UK)
Storage: Samsung - 960 EVO 250 GB M.2-2280 Solid State Drive (£106.99 @ AWD-IT)
Video Card: MSI - GeForce RTX 2080 Ti 11 GB GAMING X TRIO Video Card (£1148.08 @ Box Limited)
Case: Cooler Master - MasterBox Q300L MicroATX Mini Tower Case (£44.99 @ AWD-IT)
Power Supply: Corsair - HX Platinum 1000 W 80+ Platinum Certified Fully-Modular ATX Power Supply (£147.98 @ CCL Computers)
Operating System: Microsoft - Windows 10 Pro OEM 64-bit

I also have 4 case fans (case lies flat) with in takes as follows (all Corsair CO-9050039-WW 120mm):
  • 1 at the bottom (or side by the power supply)
  • 2 at the front
And outtakes:
  • 1 at the rear top
  • 2 as part of the H100i pro

However I'm finding the i9 runs at 90C+ under-load and the fans are on full speed. My questions are as follows:
  • Is the H100i pro sufficient for the i9 9900k or do I really need a H150?
  • Is it right to have the H100i taking air from the case and pushing this out or should I change so it's sucking cool air in and blowing the hot air into the case?
Thanks for your help!
Apr 22, 2019
Auto OC is on in bios. Everything I've read online suggests it should be running around the 80-85C mark with auto OC on though? It can quite often hit 99C.

A loaded 9900K can get very hot.
The thermal throttling point is around 100c. so you are ok there(barely)
You also have a hot graphics card installed and heat from that will reduce the effectiveness of the aio cooler.

What to do??

My suggestion is to replace the two 120mm front intakes with 140mm intakes to increase the airflow intake which will eventually exit the case somewhere taking heat with it.
140mm fans will move more air per RPM than 120mm.
Noctua fans are high quality and relatively quiet.
You could use a 1500 max rpm fan like this:
Or, a 2000 rom unit like this:
There is even a 3000 rpm unit:

You can slow down a faster unit, but you can't speed up a slower unit.