We noticed on new Dell servers that the performance was not up to par. After doing the obvious work on them we found the Bios needed and update that instantly fixed a SLOW server to a fast and peppy one, what we expected in the first place. We found this after working on a database locking issue listed below from Microsoft. Here is a link to Dells firmware and BIOS upgrade tool. As always be careful, This should be done by a qualified service tech. And ALWAYS have a a good backup! contact me if you need help.
https://support.microsoft.com/en-us/kb/2004121
Additionally, I did this registry change as part of troubleshooting today which is what at least let me get into the server and open things up before the Dell issue took control. When restarting Exchange, there will be a short delay after Windows loads before Exchange services start.