I believe you can activate AMD Overdrive or AMD Wattman in Radeon Settings, one or the other should be offered.
You can try using AMD Overdrive . But reading Overdrive CPU temperatures is a little confusing but accurate. Overdrive uses "Thermal Margins" to state the temperature.
In another words, when the Thermal Margin is at 10C, this means the CPU/APU is 10C from it maximum operating temperature. When it reaches 1c or 0c, the CPU/APU starts to throttle to keep the thermal margins above 0c. So if your APU is showing a thermal margin of 40c, it means it is 40c degrees before it starts to throttle to keep the APU cool.
So, if Overdrive Thermal Margin is showing 0c degrees, it means the APU temperature has reached 90c degrees will start to throttle.
AMD Overdrive was replaced by AMD Wattman in Radeon Settings.
You can download AMD Overdrive stand alone program from here: OverDrive™ Technology to Overclock CPU and Fan Control | AMD
I downloaded Overdrive and installed it on my computer with a FX 8350 CPU: