Aside from the lower temperature, the A9 fans have a more “spread out” sound signature even though it is running at a higher RPM and has lesser high pitched noises across various speeds. The extra padded corners also help in giving extra space when positioned in a “pull” position minimizing noise.The smaller form factors and compact builds are much more common now than ever before with many users opting to build desktops that can be portable for LAN parties or for discreet integration in their living room as an HTPC. The A9 and A8 series fans fit these application well with excellent performance and low noise profiles that is even more flexible if need be. For storage or, spot cooling or component cooling in even tighter spaces, the A4 series offers a rare and impressive feature set that is above what most people would expect from something this small.