I have a Dell XPS 8700 Intel i7-4770. I have the latest Dell BIOS, version A13, and Windows 10 Pro build 18362 with all updates installed. The BIOS Mode is UEFI.
I have BitLocker full disk encryption, even though the BIOS does not have a Trusted Platform Module (I allowed this through Windows Local Group Policy Editor).
When I power on my Dell it asks me to enter my BitLocker password. However, if I do not enter my BitLocker password quick enough my Dell powers off automatically. Recently this has become a very short time period and it isn't always possible for me to enter my password in time.