Parece que existe um problema conhecido com isso. Achei a seguinte informação no site da ATI-AMD (não tem o link porque a página é montada dinamicamente por um wizard):
Código:
No Display While Connected to the DVI Port
No Display Through DVI-Port in DOS (BIOS screens, POST, inital startup screens) With Some TFT Monitors:
If there is no display available during boot-up process on the monitor connected digitally to the DVI port and display appears when Windows is loaded, then this issue refers to a Video BIOS problem. Display should be available if an analog monitor is connected directly to VGA port or to DVI using DVI-VGA adapter.
Some users have reported that the display is available through DVI connection if a secondary VGA monitor is connected simultaneously.
* If you have a partner product (Sapphire, Club 3D, VisionTek, Connect 3d, ASUS, PowerColor, etc.), please contact your board manufacturer.
* If you have a Built-By-ATI card, please contact AMD Customer Care and one of our qualified support representatives will assist you.
Estou tentando falar com a VisionTek (fabricante da minha placa) pra tentar resolver o problema.
Obrigado!