I am using an Asus P8Z77-I Deluxe motherboard with an i5-3570K CPU and am having issues with the second display (only the TV) randomly not turning on. What i would recommend to Intel staff is to boot up into Windows 7 with only the monitor on, turn on the TV after instead of before post, right click the desktop and choose Screen Resolution, choose detect display and you should notice it will not find the second monitor (extended desktop) then work from that. (when i had an 8800 GTX it worked flawlessly)
Oh, i tried switching the cables around for Samsung 932GW monitor and LG RZ32LZ55 TV (using dvi to dvi-d and hdmi to dvi-d with most recent drivers from intel site, as experienced same from driver disc and driver on manufacturer site) but no joy.
Edit: Added i use extended desktop
New Edit: As a quick fix attempt for some people with problems, try shutting down computer, change the channels so it then goes back to DVI channel and then boot up computer. For some reason my tv seems to be picked up after (note that there is no off button on my TV - weird how they now force standby instead of proper power saving - so could be a factor with onboard graphics)