Does the iMac burn extra power with a thunderbolt display?

[omvs]

I've noticed my iMac (27", late 2011) burns a fair amount more idle power with an external DVI (or HDMI/VGA) display hooked up. iStat Menus shows the GPU power jumping by 20+watts, which I find a bit annoying... I'm guessing some power-saving mode of the GPU is being disabled in this case -- its not much less than the power when I fire up a 3D game like diablo3.

Does anyone know if the idle power is similarly high with a Thunderbolt display instead of a displayport variant? I was wondering if it might use a slightly different transport mechanism and avoid the problem....

 

[miles01110]

I was wondering if it might use a slightly different transport mechanism and avoid the problem....

You cannot drive two monitors on the same amount of power required to drive one monitor.

 

[omvs]

You cannot drive two monitors on the same amount of power required to drive one monitor.

The GPU may have to do a TINY bit more work, plus another PHY needs to be turned on. But thats not 20watts worth.

The max-power in 3D seems to be very similar with either just the internal display or with an extra, further suggesting its a bug.