There is a design problem with the Asus M2NPV-VM that doesn't allow it to recognise monitors that are attached to it through the DVI connector if the cables are too long. However, I was testing with a 3m cable and still had the same problem.

The data line of the DVI connector has pullup and pulldown resistors around 5kohm, but the CLK line doesn't have any pullup resistor or is way too big. 

To solve the problem I soldered a 4.7kohm resistor to the bottom side of the motherboard between ddc clk (pin 6) and a +5V point in the motherboard.

Now my monitor is nicely detected.

This problem is documented at Nvidia Forums. Click here to go there.

See image below: