Custom Resolution Utility (CRU)

[ToastyX]

It could be the adapter, but adapters usually have all the pins.

There's a diagram on this page: http://www.l-com.com/content/Audio-Video-Tutorial.html

Pin 12 is the DDC data pin, but you also need pins 9 and 15. Make sure the cable has all 15 pins. Old cables might not have all the pins.

If you were using a KVM switch, you'd know it. KVM switches let you use one keyboard, mouse, and display with multiple computers. Sometimes they can interfere with the DDC transmission.