4 of 4 people found this helpful
The way HPET is implemented is resource intensive and will slow the CPU down (a lot of memory reads and writes). It was an improvement for older CPUs, but for more than 10 years modern AMD and Intel CPUs support better ways if keeping time.
On modern Windows operating systems (Vista, 7, 8, 10) the OS defaults to the best available timer and that usually isn't HPET. You need to force HPET enabled to use it. HPET is really only needed for compatibility purposes (older games and applications).
In case of Windows 8 and 10, you need to enable HPET when using Ryzen Master, because in AMD CPUs the TSC is tied to the base clock (P0 state). When you change the base clock while the OS is running you break the UI compositor (Aero), so you get a black screen. Windows 7 can run without hardware accelerated Aero, so it can fall back to that.
HPET runs independently from TSC, so you can enable HPET, use Ryzen Master to test the desired overclock, disable the HPET, and finnaly set up the OC parameters in BIOS. That way you don't lose performance to HPET.