If you can hear yours and I cannot at 35%. There is no way you wouldn't hear 470 at 70% :p:. Heck at 70% for me it would be a problem based on some of the videos I watched (I've tried to find the ones I watch but can't find them at the moment). At 70% its nothing like mine at 40%, night and day.
Edit
Here is one video were the fan speed is at
67%-68% and to me it's loud. I don't hear that on my PC. Watch it starting at 1:20 when it reaches 70% up to 1:37 where it reaches 73%. It's even more noticeable. There are few more videos out there but this will do on short notice.