Well, tried to find the CPU throttling in BIOS but couldn't see anything related so then went to your Plan B. I went through all start up items and unchecked all the ones I could really do without, leaving about 8.
Tested playing music that I knew were crackling before, with the Power on High Performance...
It really has sorted the problem out! The only thing is, when I return to a Balanced Performance, the crackling reappears not as bad but still there. I guess small sacrifices

Just out of curiosity, I found a file in start up called DefaultSettingEXE Application/PLFSetI.exe. Do you know what this might be? If nothing too important, it's another thing I can uncheck to start up.
Anyway, thankyou very much all your help...it has been greatly appreciated.