Best way to stop GPU fans?

So I've been running an Asus Direct Cu II R9 290x for a while now and have finally gotten fed up with an intermittent high pitched that I believe is coming from it. It generally only starts after the GPU has been running for a while or gaming for a while but then continues to make noise even when the GPU is at idle. It's a very high pitched steady noise right at the threshold where a lot of people couldn't hear it, which makes me think it's not coil whine as the coil whine the GPU makes in game menus(400-800+ fps) sounds completely different and is much lower pitched.

I'd like to determine whether it's the fans making the noise or if it's coil whine, but to do so I'd need to stop the fans and see if the noise persists. So to get to the point what's the best way to stop GPU fans and not cause damage to the system?

just stop it with your finger by putting your finger in the middle of the fan and slightly pressing it down,
when the fan is slowing down just put your finger in the fan itself 

also it sounds like the problem is indeed coilwhine

All the DCU2 cards run very loud and hot, so it very well could be the fans

To stop the fans place your finger in the middle part of the fan till it stops. You wont hurt the fan.

  • Clean the GPU - blow out with compressed air
  • make a custom fan profile in Afterburner
  • improve case airflow.

Mine are fine. Yeah they run 1-3 degrees hotter than other 290(X)s but it isn't that bad.