Cooling Issues of my Ryzen 5 3600 CPU with H100i RGB PLATINUM 240mm Liquid Cooler

Today I received my cooler. I installed just as it is described in the manual.

However, my CPU temp still climbes up to 100 degrees Celcius while running a Cinebench R20 test.

I read the liquid temp as about 30's. I dismounted the pump and reconnected it, in case if I had a faulty install. I am using Arctic MX-4 as thermal paste.

I've squeezed the screws connected to the hooks as tight as I could.

Everything else is just operating fine. I checked the pump if it is working. I felt a slight vibration which I think means that it is functioning.

Is there a step or a trick I am missing?

Thanks in advance for all comments.

My Hardware Specs.

AMD Ryzen 5 3600 CPU

MSI x570 Gaming Edge Wifi Motherboard

Corsair Vengeance LPX 2x8GB DDR4 3200MHz Rams

Asus Turbo GeForce RTX 2070 Super Evo Graphics Card

Adata 512GB XPG SX8200 Pro NVMe SSD

Corsair Carbide Spec-05 Case

Corsair VS550 PSU

If you have bad contact between CPU and cold plate, the temps will be terrible and jumpy all the time -- not just in R20. Open a browser, huge temp spike into the 70s, etc. You also need to watch the Vcore level when running R20. If you are shooting up into the 1.50v range, that would explain the temps.

Coolant temperature is a heat in vs heat out equation, but it is like any other medium. There are no instant changes. The liquid transports the heat to the radiator to be dissipated somewhere else. If you don't remove heat as it is added, then the liquid warms up. The consequence to that is the heat is then transferred back to the CPU. Coolant temp is minimum possible CPU temp. Even on a large TDP chip, you won't see much coolant change in the 10-20 seconds it takes to run a multi-thread R20 pass. A more steady state stress test will add continual heat over time and you should see movement. I would be careful about this or flat out avoid until you are sure it is not a contact problem. Use something mild. Not the time to test out max AVX load. I like the CPU-Z "Bench Stress Test" because it is not overly taxing and it is linear. You will immediately know if you have an issue 2 seconds into the test.

Today I mounted the radiator to the front of the case working in a pull config. I mounted the front mounted two fans, on the top. They are working in a pull config, too. Now only have one fan as exhaust on the back of the case. But the temps are still same.

However when I dismounted the lids, the temp dropped to around 50 degrees C from high 60's on idle work load.

Is it normal for this liquid cooler?