The HP bios do not have any options to set speeds, that is why I mentione power management, since it does affect cpu speed and may also affect overall performance by reducing clocks when computer on stand by. Other than that there is no other options, bios is pretty basic
The only thing I can figure out is the ram compatibility, it should be a PC3-12800, the sticks are PC3-12800 so the only remaining options are if timings or anything else is not matched, causing this problem.