Neki dan sam i ja tražio razlike između 40 i 80 pinskog kabla. Zaključak je: wikipedija je zakon

http://en.wikipedia.org/wiki/Parallel_ATA

ATA's ribbon cables have had 40 wires for most of its history (44 conductors for the smaller form-factor version used for 2.5" drives), but an 80-wire version appeared with the introduction of the Ultra DMA/33 (UDMA) mode. All of the additional wires in the new cable are ground wires, interleaved with the previously defined wires to reduce the effects of capacitive coupling between neighboring signal wires, reducing crosstalk. Capacitive coupling is more of a problem at higher transfer rates, and this change was necessary to enable the 66 megabytes per second (MB/s) transfer rate of UDMA4 to work reliably. The faster UDMA5 and UDMA6 modes also require 80-conductor cables.