According to the information on thinkforum(>60days old):
X40 is OK with SSD, no any problem.
Both X41 and X41 tablet will beep twice on boot up and give incompatible
hard disk error message.
You can click "ESC" to continue boot up or change the bios setting to let it
show error message 5 seconds, and the machine contiue boot up by itself. If
you turn off the volume on boot up, you will NOT hear the warning beep, but
the error message still show until you hit "ESC" . Windows will start up as
norm