I've had my PC since January 2018 and have never replaced the CPU thermal paste. I also haven't thoroughly cleaned out the dust since last year. Performance was fine until recently, but the weather has become hot and dry, and I've started playing Microsoft Flight Simulator 2024, which puts a heavy load on the CPU. The system has begun lagging, and monitoring it with iCUE showed the processor reaching around 100°C. Could the old thermal paste, accumulated dust, or the CPU cooler be causing this? I have fresh thermal paste available and would appreciate advice on what to check and replace.
3 Answers
The type and condition of the cooler matter too. If you’re using an all-in-one liquid cooler, check that its pump is running and that the radiator isn’t clogged. For an air cooler, verify that the fan spins properly and that the heatsink is firmly mounted. If fresh paste and cleaning don’t lower the temperature, test with another known-good cooler.
A sustained 100°C reading means the processor is likely thermal throttling, which can explain the lag. Don’t assume the CPU itself is failing yet—confirm the temperature with a hardware monitor, check CPU usage and clock speeds, and make sure the cooler is connected to the correct fan or pump header. Room temperature can contribute, but it normally shouldn’t push a properly mounted cooler straight to the limit by itself.
Start by shutting the PC down, cleaning out the dust, and making sure the fans and heatsink or radiator are unobstructed. Then remove the cooler, clean off the old compound, and apply fresh thermal paste before remounting it evenly. Several years without replacing the paste makes this a sensible first step, especially with a demanding game and warmer room temperatures.
You don’t need to clean it every week. A thorough cleaning every few months, or when dust is visibly building up, is usually enough unless the room has pets, poor filtration, or unusually dusty conditions.