On my D2500CC with current bios it only happens with 9.0R/amd64. I can
successfully boot 9.0/i386 with minimal (single character) graphics
corruption that can be worked around by switching syscons to 640x480.
Unfortunately serial console goes blank as soon as kernel begins
execution (both i386 and amd64). Trying to use conscontrol or "sysctl
kern.console" gives "Device not configured".