While searching for an answer, I found this question on SU what is the purpose of this 4 pin interface on sata hdds and why doesnt it exist on SSDs?
Well, on my Kingston HyperX SSD drive, they do exist.
So if Spread Spectrum Clocking and reduced power spin up is not needed, what would be the function of these four pins?
All of my search attempts show only a few variants that apply to 2.5" spinning platter drives depending on vendor and none for SSD, to include the attached SU question.
Any ideas?
Best Answer
The pins are manufacturer specific and used by both the manufacturer and data recovery experts to access the System Area of the drive. Sometimes those pins support a serial interface, in which case you can attach a 4 pin cable (power, ground, transmit, receive) and talk to the hard drive. Data Recovery hardware, such as a PC-3000, might use these pins to update/repair the firmware on drive, remove an ATA password, or modify/clear the G-list.