Externally both models are very similar. Shape and dimensions of the housing and the terminals are identical. When K model only the narrow side surfaces are no longer smooth / rough but shiny / matt like the rest and the keyboard no longer silver mirror but shiny black. In addition, the keys are no longer lit and the wireless indicator light is missing.
Basically, the fan of the PS3 is not inaudible, as sometimes described. The fan speed is temperature dependent controlled. The first 15 min. After a cold start can hear the fan in the first speed stage but hardly or only at close range (less than 1 m distance). If the PS3 is getting warmer, the fan starts in the second stage and is a little clearer to hear (but only when switched off sound on TV). Between J and K model was only a small difference in the noise level; the drive noise were subjectively equal. Drive access is clearly audible at normal background noise in movies or games, but occur rarely or only at the beginning on. The J-model was a bit warmer in the play mode, which is why the fan speed was higher and minimally louder than was the K model (both units were completely free). The K-model was even after several hours behind the vents only lukewarm.
That's why I chose the K-Model CECH-3004B. Apparently scatters the intensity of operating noise, even within a device series, perhaps the J-model was only by chance a little louder. Overall, the difference between the two devices that were available to me, only minimally.
