Server 2012 unexpected restarts

Our Win 2012 server has started to restart at random times with an Event-id 41 Kernel-Power message.After a week it was getting worse and sometimes the server would reboot consecutive times.We didn't have a backup db server so this was chaotic!

Supplier of server said it could be the power supply so we replaced it.Immediatly it made a difference.It was stable for about 17 hours before it randomly restarted again with the same Event id 41.After that it was about stable for 6 days without rebooting.

I then installed some important updates on the 6th day which prompted me to restart server.I restarted and waited (This was done remotely).After 13 minutes the server was still down.When i went to server i saw server shutting down with error message..."page_fault_in_nonpaged_area" and then it rebooted again.After server became stable again and saw the dreaded Event ID 41 message again.The server had restarted twice after i rebooted server initially.
I don't think the updates caused this error as the server has been stable for two hours after update?
Maybe there's another underlying hardware problem that's obviously very difficult to pinpoint?
What else can i check?