lurcher

So, I've just updated my system to a Mac Pro 2010 with a 12 core 3.46Ghz processor and 48GB of 1333Mhz memory upgrade from CreatePro. It's running latest Sierra and Logic Pro X. I did a fresh install of everything, DAW, Sample libraries etc. System disk is a 500GB SSD on a PCIE card and all the content is on a 750 GB SSD. Now I'm noticing a not very loud but definitely there burst of noise at random intervals, like a faint 'chick' I load up a new project and only load in say Retro Synth, no noise until I play something. Then at random moments i can hear it. I've looked at various other forums/posts and it has nothing to do with flex or fades and the CPUs don't look like they're spiking and neither should they! Has anyone else noticed this?? Can anyone help cure the issue? Many Thanks in advance for any help.