Always been like that, the noise is a recent happening, the past week or so. It gets louder and quieter at random. Holding the res or tapping it with a spanner makes no difference. I'll leave it as is over the holiday period and replace it in the new year with something similar to what I have on the GPU loop (as shown in sig). At least if it does go pop I have a Megahalems in my spares box.