Played around with undervolting yesterday. Currently got it down to 0.85v at ~1915 with performance pretty much the same (was boosting to 1950mhz stock). GPU temp peaks at 64c but is usually lower, memory peaks at 84c, which is great for my SFF case. Stock fan curve so still playing around with that but impressed so far.
Undervolting helps a bit with the coil whine too, although it's still noticeable even at low FPS. Any load above 250w and it'll start to creep up in volume.
Not experienced any coil whine myself thankfully, the fan isn't the quietest at higher RPM though.
Testing OC with Kombustor, VRAM reached 106C and GPU 86C :O bit unrealistic though, so far in games the GPU hovers around 80 and clock sticks around 2100