The problem

You're booting Linux on your new Supermicro mainboard (mnotherboard) and after some of the boot message from Linux it suddently only displays "No Signal" on your external Screen and/or KVM console.

The solution

Add the "nomodeset" to the kernel flags in GRUB (or LILO/Syslinux/...).

On Debian you will have to edit /etc/default/grub:

GRUB_CMDLINE_LINUX="nomodeset"