Right, sorry for late reply and sort of a necro, but i got round to having a test around with things, i was having this noise "posted in top post" again, so i thought id take the side of the case off to see what it was exactly, funny enough it "seems" to be the GPU almost, i could be wrong.
But what was really strange was when i took the side off the case, the noise stopped after maybe 10 seconds. It leads me to think its either a cooling issue, or the case its self.
The temps stayed around the same with the case off as they did with it on. So im a little weirded out.