From the link: http://en.wikipedia.org/wiki/Extended_display_identification_data
The EDID is often stored in the monitor in a memory device called a serial PROM (programmable read-only memory) or EEPROM (electrically erasable PROM) and is accessible via the I²C bus at address 0x50.[1] The EDID PROM can often be read by the host PC even if the display itself is turned off.
How can I read that information?