XPS 8930, S2719H, no signal from your device

I experienced, and do experience, the 'no hdmi signal from your device' on my XPS 8930/2719 combination. I tried reversing the cable, as advised elsewhere on this forum, and this seemed to be an improvement at first, but it is difficult to tell whether the reversal actually made a change.I should add that dodgy cables is not what one would expect from a premium product like Dell.

After about a dozen restarts, initiated by myself, the system seems to have settled down, and whilst the 'no hdmi signal' notices are still presented, I feel the message was and is profoundly misleading, and I found that restarts initiated by myself generally resulted in the sending of a signal within 10 to 20 seconds. Quite why it takes a modern monitor so long to recognise a modern PC is actually sending a signal is a complete mystery. It is not possible to tell whether bashing the keyboard or wiggling the mouse helps in this recognition process. (I get the impression the monitor message indicating that will be all that is required is utter garbage, i.e. nothing will speed up the natural snail's pace.)

The real problem however is with restarts initiated by Win10 in response to an installed Win10 update (and many of these can involve multiple restarts). In these cases, the wait to recognise the hdmi signal often takes several or many minutes. Again, it was impossible to tell whether bashing of keys or mouse-wiggling did anything to help. The mystery in the case of Win10-initiated restarts is that there is obviously a signal being sent, because once the recognition starts, a typical screen (e.g. 'update in progress 27% complete') indicates the PC is sending stuff to the monitor.

Needless to say, I am extremely disappointed with my my new Dell. There seems to be a serious lack of communication between PC and monitor, and an even more serious lack of communication to the hapless user. I was scared to switch the PC off in case it might never display itself again, but I now realise that the 'no hdmi signal' is a probably a completely stupid message.

Or maybe hdmi is just a rubbish protocol?