If your CPU is running at prolonged speeds and reinstalling Windows didn't solve the problem, there could be several reasons for this. You should check the CPU temperature, power settings, for malware or viruses, and background processes. Additionally, updating the BIOS and drivers could help resolve the issue. If none of these solutions work, your CPU or motherboard may have a hardware issue. In that case, you should contact HP support or take your PC to a professional repair shop for diagnosis and repair.
PC Hardware Specialist