48c is absolutly fine, your good upto 65c under full load.
Go into your Bios and sisable the EIST function/Intel Speedstep which is slowing down your CPU speed as shown in CPUz.

Those temps are very low considering the voltage going through the chip.
Check with Coretemp as well as Intel TAT. Bear in mind that some board report lower temps whilst others report higher temps. None are really 100% accurate.
