Fan whining noise on stock I5 6500 cooler

Just bought all the goodies on here to make a new PC for a friend, all worked great and she is up and running but the fan is making a noise like a drone is in the room. Is this normal? My old I5's have been silent, with no pitch changing at all under load, as far I can tell.

Sure you've checked, but any wires snagging on the fan?

Yeah, I checked, even gently moved the cable out entirely in front of it so I could be 100% certain and it's still the same unfortunately.

If I wiggle the fan gently at different points the sound changes a bit, a bit more muted at some points, but I don't want to take the thing off unless I have too since I have no thermal paste immediately to hand to put it back on.