Resolution issue with macbook pro 13 (late 2013) and dell u2711

I have a Dell U2711 (native resolution 2560x1440) that I use without issue with a macbook pro late 2007 (running 10.10.x), various iMacs and Macbook air 2011 running 10.10. When I say without issue, the display works at its native resolution.

Last week we got a MacBook Pro 13in, late 2013 model.

If I connect this macbook via either thunderbolt connection to the u2711 using either DVI port on the dell, the maximum resolution that I can use is 1920x1080. I am using apple mini displayport to DVI adaptors (I have tried 2 different ones and 2 different DVI cables, with no improvement). Clicking option + scaled in sys prefs does not give the native resolution as an option.

However, I just discovered that if I use a DVI to HDMI adaptor and I connect the macbook to the display I get the full native resolution without issue (2560x1440).

I have zapped the pram, powered down the display etc etc etc and it made no difference.

I would prefer to use the mini DIsplayPort to DVI adaptor rather than HDMI, any suggestions appreciated.

TIA.