I have three Benq GW2765 monitors which periodically report “No Signal Detected” for DisplayPort even when the computer it’s attached to recognises the monitor is present (displaying it in the monitors/displays list etc). Changing the DisplayPort cable or plugging it into a different computer doesn’t help (I tried with both Mac OS X and Linux/Fedora machines), but HDMI and D-Sub connections work perfectly (but can’t support the full screen resolution). I can even disconnect a cable from a working monitor, plug it into a non-working monitor and it will continue to complain about no signal, but plug the cable back into the working monitor and it carries on working fine.
The solution turns out to be quite simple – unplug it, wait for the power indicator light to turn off and turn it back on. It will then detect the DisplayPort signal correctly. Unplugging the DisplayPort cable and plugging it back in will not help, nor will turning the monitor off with it’s power button. Briefly disconnecting the power cable and reconnecting it isn’t enough, you have to wait 5-10 seconds for the power indicator light to turn off.
Naturally that means that you can do all kinds of due diligence testing at home before deciding it’s a hardware problem and returning it to the shop. When you get to the shop it will work perfectly because it’s been unplugged on the car trip.
So that was fun…