Alright I will sum up the 3 display experience I have faced with this board.
First, I plugged in the HDMI to DVI to my U2412M which is a 1200p monitor everything works fine in 1200p res including the new BIOS screen.
However, after I installed the display driver of the board, the 1200p no longer receive the signal from the board. I tried driving 2 other display, 1 in 1080p(Samsung TV32") via HDMI to HDMI, and BenQ 20" 900p, both works fine. After that, I bought a Display Port to Display Port cable to plug in the 1 remaining display port on Z87x oc to my U2412m. From then, I can run 3 monitors with the driver installed.
Anyway, several flaws within the board are still remain questionable. To begin with, the bios has not shown on my main U2412M, instead, it appears on the BenQ 900p screen. This may be my flaws but I really couldn't find any option in the bios to select which connection will display the bios. If I unplugged all other screens and connect with only U2412m via Display Port; The bios will shows up but at the 1080p not the 1200p native resolution as prior the the driver installation. Another flaw is that why the 1200p screen does not work after I installed the driver. If it didn't work prior to the installation of driver too I would blame the limitation of HDMI to DVI cable but this is not the case; the monitor works and the bios also displays the correct resolution before the driver installation.
In sum, 3 displays driving with this board is possible but the weird problem I have encountered so far made me unable to recommend it as a HD4600 choice. On the other hand, this board target market is not the consumer who will use the integrated graphic solution, so I think it is acceptable board. If you are a special case who does it, my recommendation is not to use the monitor of over 1080p calibre.
