My PC recently started showing unusually high CPU temperatures. The system has a Ryzen 9 5900X, a roughly two-year-old Corsair H170i AIO, and an MSI RTX 3080. I have reapplied Noctua NT-H2 thermal paste twice and remounted the CPU block three times, but temperatures still reach about 88–90°C in vanilla Minecraft and sit around 86°C while playing Final Fantasy XIV. The temperatures were similar yesterday, and I'm not sure what else to check.
2 Answers
Check the position of the pump and radiator in the loop. The CPU block or pump should not be the highest point, since trapped air can collect there and reduce cooling performance. Also verify that the pump is running at the expected speed and that the radiator fans are spinning properly.
The 5900X can run fairly warm, but temperatures in the high 80s during light gaming suggest checking more than just the paste. Confirm the block is making even contact, inspect the radiator for dust, verify pump and fan speeds in BIOS or monitoring software, and check whether settings such as Precision Boost Overdrive are pushing extra voltage. If the AIO is losing performance after two years, the pump or coolant flow could also be the issue.
The tubes leave the block on the right side and run upward and to the left toward the AIO radiator, so I’m checking whether the pump itself is ending up above the radiator.