What is the function of the four pins on my SSD?

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.

Partial Answer

I emailed Kingston technical support to get their answer on the subject

Thanks for contacting Kingston technical support. For those 4 pins, basically they do not have any function. Only SATA connector and power connector of SSD will be connected and used.

I Pushed for more information and got this in reply

Thanks for your reply. Our apologies but they are intended for any use or purpose.

I will make note that in the footer from the email It had 下午 2:02 (下午/xiawu means afternoon in chinese) so this information has come from china and I believe the first point of contact team is trying to say is that the port is not intended for any use or purpose but have done so in poor English however this is an assumption.

Personal thoughts:

I suspect that they are for development/recovery use as I noticed on a picture of a stripped down OCZ Vertex 3 SSD they had 4 un-soldered points on the board in the same location as OP's SSD labeled vcc, tx, rx, gnd

• VCC - Power supply pin
• GND - Ground
• TX - Transmission of data
• RX - Receives data

Note: This SSD is using the same NAND controller SandForce 2281 as the drive shown by OP as per OCZ Vertex 3 tech specs