For the S15S Notebook are 6 different Version in market.
The S15S was changed from S15SN(S15ST1) to S15ST4(S15SNē) to S15ST5(S15SNē).
The S15ST4 & S15ST5 need a new Bios, the old Bios from S15ST1 isn't compatible with the S15ST4 & S15ST5.
Also the S15S need separate Bios for WXGA & WSXGA+ LCDs; total 6 different Bios Revisions.
Some more Information about S15S ST1, ST4, WXGA & WSXGA+ issue:
- all units who had an WSXGA+ LCD inside had a small Sticker on the bottom with "WSXGA+", the WXGA Version doesn't had such kind of Logo.
- all units who had a Serial number with SY8501****** or higher are S15ST4 or S15ST5, all with older Serial numbers are S15ST1.


S15ST1 Bios = Rev. 1.xx
S15ST4 Bios = Rev. 2.xx, 3.xx
S15ST5 Bios = Rev. 2.xx, 3.xx