I build a fermentation chamber that has a small computer fan that is equipped with tiny blue led lights. Is it only UV light that can skunk a beer? What would the effect of this frequently run fan light be?
Here is some great information about beer skunking based upon wavelengths of light (http://www.safespectrum.com/applications_beer_wine.php). UV is the strongest light source that will cause beer skunking. However visible light, specifically anything under 500nm or thereabouts, are threats for beer skunking. And from this page (http://www.oksolar.com/led/led_color_chart.htm) you can see that blue light emitting diodes (LEDs) have their wavelengths under 500nms (470 or 420nms). Thus the blue lights on the fan could be a problem, but based upon the exposure time and brightness of the lights will determine the effect on the beer. Pale colored beers and very hoppy beers will have the most dramatic effect if there is an effect.
Why don't you just replace the fan with the lights with a normal fan, or place the computer on the outside of the fermenter. Also aren't you worried about the heat production by the computer? Or the possibility of the fermenter blowing off and ruining your computer? Seems like it would be prudent to place the computer on the outside.