Under 100°C it should be fast; are you sure the measured temperature is correct? Have you tried monitoring it with another utility like Speccy? Does the frequency drop when it reaches 47°C? Is there a setting in the BIOS where you cold set the limit to 47°C and force it to slow down once it gets warmer? Unfortunately your system may be too old to be compatible with Intel XTU, but it costs nothing to give it a try.