I have to admit that my recent build was to have a windowed case and the fans all had blue LEDs, even the processor cooler. That one my son liked so much I gave it to him, he was due for a new one any way. My personal new build is windowless, but it does have a mesh around the perimiter walls for cooling and the blue LED's from the processor fan just add a soft glow to it, just barely visible.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70