Solved (i think). For some reason I cant edit title as Mod as already edited it in the tags.
So last night I was checking the bios version which looked to be current. While I was in the bios i decided to tweak (turn on and off randomly) some of the settings. I really should have done them one by one to check which one if any would work, but I didnt. So I turned USB Audio off, a C state setting to off and probably a couple of other things which dont come to mind right now. I also enabled GNA and installed drivers for it. Fired it up and interference totally gone.
I restarted a few times, ran Cubase, opened browsers and all quiet.
So if anyone has similar issues I am happy to back track and enable/disable the various bios changes I made to pinpoint the one that actually worked. I am thinking possibly the USB audio one?
Thanks to all above for advice.
By the way the reason I say solved (i think) is because yesterday I had to send my mobile phone for repair. I know mobiles can interfere so i tried leaving the phone down stairs and I may have even turned it off. So if the issue comes back when my mobile returns I will know its the phone.