I have a Z77 chipset Asus P8Z77-V Premium motherboard with Displayport, HDMI and Thunderbolt video output. I recently purchased a new monitor LG 24GM77-B which can run at 144Hz or 120Hz with a strobe backlight which I find best as it significantly lowers blurring which I find intolerable on the majority of LCD monitors.
I have started using Displayport as it provides the 120Hz that I need, whereas HDMI only provides 60Hz however I am having big problems with the display going totally blank at random times when power saving. It will work find after rebooting for hours and then the display will power down and refuse to awaken. No mouse movement or keyboard input will awaken the display. I have powered down the display pulled the plug but it refuses to resume and show a display.
I removed the Intel graphics driver that was installed and installed the latest. I even did a driver clean to remove all remnants of the old Intel drivers but it made no difference.
I do also have one of the HDMI connectors on the monitor connected to the HDMI port on the motherboard and I have set the display to mirror to the two connectors. Now since doing this I can access the HDMI connected display and it does show a picture when the displayport connector just powers down the monitor so there is at least one display working. It's just the displayport which is a problem.
I never had these problems when using DVI-D on my older X48 motherboard with nVidia graphics card, it is only displayport which has a problem. I have checked the cable and it seems okay and I think it was displayport pin 20 which needs to be not connected which did seem to cause some people problems. I did try and test for a connection but I cannot be certain that it tested successfully due to having to test it with a piece of wire into the connectors to test for a circuit. The cable was totally disconnected when I did this!
The Intel driver shows as 10.18.10.4425 in device manager and about 4 months old. This is with Windows 7 x64 SP1.
I am stuck as I keep having to switch to HDMI with only 60Hz as the displayport keeps causing problems. I do also have some problems when booting my PC as the displayport seems very flakey during booting too. It only seems to work when inside windows on the windows loading/logo screen. I do have windows on a boot menu and that frequently does not show on displayport but does on HDMI/DVI-D. It's as if the driver enables the display which seems disabled earlier.
As I post this I am having to use HDMI as the displayport has failed yet again.