You have to remember that although 50degrees is quite hot, I believe AMD CPU's have a thermal ceiling of 75degrees (although running it close to those temps for long periods of time would not be recommended). The other thing you have to realise is that temp sensors on motherboards are not calibrated, a temp sensor on one motherboard might read as CPU as being 45degrees while another board could read the same CPU (and cooling solution) as reaching 50degrees.