Any suggestions as to why my Linux workstation randomly crashed?
 

from /var/log/messages:

Apr 27 11:18:47 s1k gconfd (drk-2958): Received signal 15, shutting down cleanly
Apr 27 11:18:47 s1k gconfd (drk-2958): Exiting
Apr 27 11:19:32 s1k shutdown[3712]: shutting down for system halt
Apr 27 11:19:32 s1k init: Switching to runlevel: 0
Apr 27 11:19:33 s1k smartd[2723]: smartd received signal 15: Terminated
Apr 27 11:19:33 s1k smartd[2723]: smartd is exiting (exit status 0)
Apr 27 11:19:34 s1k xinetd[2362]: Exiting...
Apr 27 11:19:35 s1k automount[2315]: do_umount_autofs_direct: couldn't get ioctl fd for direct mount /decp
Apr 27 11:19:36 s1k kernel: usb 1-6: USB disconnect, address 4
Apr 27 11:19:40 s1k kernel: Kernel logging (proc) stopped.
Apr 27 11:19:40 s1k kernel: Kernel log daemon terminating.
Apr 27 11:19:41 s1k exiting on signal 15

it looks like a normal shutdown. there is no any error...

What is the issue right before the Apr 27 11:18:47 s1k gconfd (drk-2958) ?

I'd start at bios. See if there are any logs there. If you set any settings then you may have to change them to failsafe or default. Might have to run memtest for a few days. Might have to run hardware diags for a few days. Run system in hot cold chamber even. Test power supply and test temperatures. See bios also for any warnings on temps. Like beep on temp before shutdown on temp.

Most boards were never tested at the factory on linux. Almost no board is certified to work. Just because windows works doesn't guarantee that linux will. Different timings and way that data is moved can render a board useless to linux.