Hi @c_bator!

We are sorry to hear about your problem. Can you please send me your Service Tag on a Private Message so we can look further into your case? 

If they replaced the heatsink then typically that would come with new fans as well as they are all connected and it's a PITA to remove the fans from the heatsink.  I can't seem them replacing JUST the heatsink and not the fans but I guess it's possible? 

Call up support again or PM the rep that responded to you and hopefully they can get you sorted out.  

I think you're right, they did replace the fans with the heatsink. Just wish the parts list indicated that.

...,and that is wasn't returned with the same problem it went it to get fixed.

Chances are it's a whole new heatsink , fans included which is even more odd....I would think the odds of having two bad fans on two heatsinks in a row are pretty slim.  As much flak as the Alienware heatsinks get, faulty fans are not usually a problem. 

Any ideas what else it could be?

New behavior...... I can stop the noise by muting my system. The noise can occur while muted, but toggling the sound will stilll stop it.

maybe a sound / speaker issue? What would cause this?