I finally found a program that does exactly what I want it to do, RivaTuner, although it needs to have Everest running too to get the CPU temperature, but that's not a problem as I already had Everest. It was pretty complicated to set up but it works well. However, there one very big problem, which is that it works in every game I have tried except SAMP and this is extremely annoying. Even if I play normal GTASA it works fine, but when I play SAMP nothing shows up on the OSD. If anyone knows how to get it working or knows another program that may work with SAMP, let me know!
Just to show you what it looks like when it works, this is a screen shot from normal GTASA:
