I suggest you to test with the new Hazro display connected the the DVI port on the system and with the older monitor connected, boot to the operating system and try to set a Multi-monitor configuration as extended desktop with the instructions posted on the following site:
From there you can confirm if the system is detecting the video monitor at all.
Additionally make sure that the internal settings for this TV are set to pick the DVI as the video input. Also try using a DVI to HDMI converter and see if your system is able to detect it that way. Try another DVI-D monitor in your motherboard to confirm that this port is working fine too.
Thanks for your reply!
I did what you suggested, with the following results:
When I'm using an HDMI to DVI Cable with the HD Graphics port, the old screen (a NEC 20WGX2 btw) runs normally as with a normal DVI Cable. The Hazro, unfortunatly, remains black. The DVI port works with the old screen, too.
Then I plugged my old screen into the HDMI port and the Hazro into the DVI (the latter one after Windows had finished booting - otherwise both screens would have remained black). I then followed the instuctions you posted and the Hazro was recognized as a QHD270. Sadly, the screen remained black either in cloning mode or in extended desktop mode.
When I look under Display-> general settings there is no resolution shown in the drop down menu (not even a small one like 800x600 or sth.) When I try adding a resolution (2550x1440 @ 60 Hz or even a smaller one) there always comes an error message, saying: the user specific resolution exceeds bandwidth (I hope I translated everything right), no matter what timing standart I choose.
Your ASUS motherboard has a single-link DVI port, with a maximum resolution of 1920x1200@60Hz. The monitor requires dual-link DVI for its native resolution.
I couldn't find the datasheets for the chipsets so I cannot be sure, but I suspect that no Intel chipset supports dual-link DVI. Otherwise, why not implement it on the motherboard.
The only hope of connecting the monitor to your motherboard seems to be through an active Displayport-to-dual-link-DVI adapter. That is a costly endevaour.
Or you can just buy a graphics card with dual-link DVI, it may actually be cheaper.