Question
What is the SATA speed of ThinkPad T420?
Answer
The T420 (T420s and T520) is capable of having 3 different internal storage devices.
1) The main harddrive bay (9.5 mm thick 2.5 inch SATA) is a SATAIII (6 gbps) connection.
http://www.flickr.com/photos/60081959@N04/7894501528/
However in order to fully utilise the SATAIII connection, you must have a SSD that is capable of SATAIII speed.
2) The optical drive bay (Ultrabay Enhanced 12.7 mm thick) can also handle a harddrive (platter or spinning) of 2.5 inch format (9.5 mm thick) at SATAIII speed.
3) the WWAN slot next to the DIMM RAM ram slot on the bottom of the T420, is capable of handling mSATA available size on the market (as of 2012 August), but it will only run at SATAII speed (3 Gbps) even if you put in a SATAIII mSATA.
http://www.flickr.com/photos/60081959@N04/7894503440/ <--- a SATAIII Samsung mSATA running at SATAII speed within the T420 WWAN slot.
