I built my PC about four or five years ago, and its performance has declined noticeably. The CPU seems to sit around 70–80% usage, so I'm considering a factory reset in case background software or malware is responsible. Before doing that, I'm wondering whether replacing the thermal paste might help. How often do you normally repaste a CPU, and what should I check first?
4 Answers
First, confirm whether you mean 70–80% CPU usage or 70–80°C temperature. Those indicate completely different problems. If usage stays high while the PC is idle, open Task Manager and identify which process is consuming the CPU. If the temperature is high, check the cooler, fan operation, dust buildup, and airflow before assuming the paste is bad.
Most people only repaste when removing or replacing the CPU cooler, or when temperatures become unusually high after cleaning everything else. Good paste can last roughly five to ten years, and some systems go much longer without needing a replacement. Thermal paste doesn’t actively cool the CPU—it just improves heat transfer between the chip and heatsink.
I’d treat repasting as maintenance rather than a regular schedule. Clean the case and cooler first, then compare temperatures under the same workload. If temperatures are still significantly higher than they used to be, or the CPU is thermal-throttling, repaste it and make sure the cooler is mounted evenly. Otherwise, there’s no need to replace the paste just because several years have passed.
Usage depends heavily on what you’re doing. Around 80% CPU usage during a demanding game can be perfectly normal, while 80% usage sitting at the desktop is worth investigating. Check CPU temperature, clock speed, and the specific process using the CPU. A fresh operating-system installation can be a useful troubleshooting test, but repasting won’t fix malware or excessive background activity.
Ambient temperature matters when comparing results, so try to test in similar room conditions and with the same workload.