Windows Server 2008 Critical Failure

I have been having an issue with 1 of my severs sporadically since September of last year. I will come in, in the mornings and the server will be in a reboot sequence saying it was shutdown due to critical error and have to press F1 to continue. When I check my error logs it says "The computer has rebooted from a bugcheck." Then a bunch of bugcheck code and says it was saved in the memory.dmp file. From what I can tell this Is the reason the server is shutting down, problem is I'm not sure where to start to correct the problem. It is a dell server and I have already contacted Dell previously and they came out and replaced the mother board because it was showing a CPU error. However this didn't fix my issue, does anyone have any ideas? Would this be something I just need Dell to fix or is it something that I will have to do myself?