Hello, I was able to resolve the issue by upgrading the BIOS from 4.9 to 5.7.  To perform this I needed to load the Factory image and then run the OptiPlex_5040_1.5.7 utility.  This needed to be done from the factory image since I was unable to reboot the machine correctly when loaded with Windows 1607.  Things are now working well with Windows 1607 deployed via SCCM 1606. 
Hello, I am testing a Dell OptiPlex 5040 with Windows 10 x64 and am having an issue where each time the machine reboots, it sleeps or hibernates instead of booting back up.  I do not see the Dell splash screen.  The power light on the desktop remains on until I power it down and start it up again. I have tried removing all USB devices, removing multiple displays and have updated drivers however the issue continues.   I have also tried Enabling Block Sleep and Disabling Deep Sleep in the BIOS.Has anyone run into this? Thanks - Scott 
OptiPlex 5040 desktop sleeps during a reboot