Thinkvision pro 2840m - no signal on DisplayPort and MiniDisplayport - mid2011 27" iMac

Question

Hi Guys,
I have the thinkvision pro 2840m for a week now and I have fiddling around with the display quite a lot.
The display only gets a signal from my iMac 27" (mid2011) using midisplayport to hdmi @1080p
if I try minidisplay to minidisplay - the iMac recognises the pro 2840m but there is no signal on the screen.
if I try minidisplay to Display - the iMac recognises the pro 2840m but there is no signal on the screen
if I try DisplayPort to DisplayPort from my wife's thinkpad T410 it recognises the pro2840m but there is no signal.
from above, I am very disappointed that I am only able to get a 1080p resolution, and not atleast the iMac native resolution.
I know that my iMac is older and it does not support 4K yet, but atleast it should give the native resolution of the iMac which it is not ...
did any of you guys experience this ?
I have spoken to support, nothing helpful from there.
Please help...
Thank you

Answer 1

Hi,
It might sound silly, but you know each time you connect a cable to a different input on the back of your display, you need to switch to that particular input cycling through the inputs by pressing the button on the far left of all buttons with the 1-><-2 symbol?
The mDP-mDP cable should work for you just fine. And for the T410, you need to set the display to DP 1.1 mode in the display menu under OPTIONS.
Hope that helps.