restart only restarts the cgminer process reboot does a complete reboot of the os
Both of your cron entries are correct for 8 am and pm, the question was for every 12 hours
Geez, difficult much? LOL
I see that the question was 12 now. Didn't see your post before I posted mine, so chill.
I see restart affecting my hash line (trail off in hash graph). I do not see the same thing with reboot, so I question what you are saying. This works for me. That is all.