hi,
there is no relation between monitor-power-safe-mode and
disk-case.
Also if you have a PC without disk, your pc at bios level
gives signal to video, that passes from power safe mode
to normal mode. You can see BIOS info, logo, and bios-devices menu, prior that the system acess the disk and
the Operating system.
If your monitor ramain in p.s.m., probably it is not
well wired to PC or it has some front-switch moved
(for multi-cable possibility) or your PC has more than one VGA port (the original + the new VGA adapter) or unforunatelly, you have broken 1 of the pins in the male cable connector of the video.
good luck