Hi,
We have a few 2848 switches, and every now and then I'll get a nagios alert that the uptime on the switch is less than an hour. Sure enough, I login to the web UI and see the switch has rebooted.
I don't deal with much Dell gear, so I'm not sure where to look for a reboot reason on these things. I don't see a system log in the web UI nor an equivalent of "sh ver" from Cisco that would list whether it was a software crash or power loss.
I don't suspect it's power since we have a ton of other stuff in the rack and these two switches are the only things that reboot on their own.