I have basically the same overclock as you, I have MSI afterburner running the fans near to 100 though :/
I've read at
https://github.com/ckolivas/cgminer:
Fan control in auto fan works off the theory that the minimum possible fan
required to maintain an optimal temperature will use less power, make less
noise, and prolong the life of the fan. In auto-fan mode, the fan speed is
limited to 85% if the temperature is below "overheat" intentionally, as
higher fanspeeds on GPUs do not produce signficantly more cooling, yet
significanly shorten the lifespan of the fans. If temperature reaches the
overheat value, fanspeed will still be increased to 100%. The overheat value
is set to 85 degrees by default and can be changed with...
If I were you I would play with undervolting the GPU (easier in Windows), that should lower
the GPU temp therefore fans won't run 100%, and there should be significantly less
"burned" plastic.
Thanks for this post, I will change my rig with those specifics in mind. I have them intentionally running near 100 as I thought, higher fan speed, better cooling etc. I'll just move the rig near a window and build some kind of vent to send the flow out the window. Thanks!