How to connect HP x360 spectre laptop to HP Envy 34" ultrawide monitor?

[ken2esq]

I have a 2016 HP x360 Spectre (the 15 inch) with 4k monitor.  I just bought an HP Envy curved ultrawide 34" monitor.

This laptop has an HDMI port, so I connected the laptop to the monitor via HDMI cable.  At first the monitor said something like "no signal" then it flickered with a sort of duplicate of my laptop screen, then went dark, then gave me another "no signal" message, then flikered, then another sort of duplicate of my laptop screen. These duplicate images only last a second, then the part where it is dark or saying "no signal" lasts about 8 seconds.

Meanwhile, after I connected the monitor, my laptop screen also started flickering every 8 seconds or so, kind of like when the ultrawide flickered the screen for a second, that was when my laptop screen would flicker dark.  In addition to the annoying flicker, my laptop display settings also got funky, presumably from the ultrawide pushing settings onto it?  I don't know, but suddently things were zoomed, and screwed up.

I went into display settings and advanced, and lowered the resolution to something I knew was within the scope of the ultrawide, in case that was the issue.  While that did change my display a bit, it was still funky and flickering the same way, no fix.

I also tried switching to using only the external monitor, did not help.

I have read the HP guide on using an external monitor with an HP notebook, and I did everything it said to do, and it simply does not address this problem.

Thanks,

Ken

[banhien]

@ken2esq

Hope someone can give you more information but from our tests with 3 HP x360 machines (they arell 4K screen, 2 are 13") early Jan 2017 using my 4K TV and HDMI (my TV has 4 HDMI ports, only 1 port is available for 4K input).

We tested both 1.4 and HDMI 2.1 cables to connect them but NONE of them could display 4K.

Regards.

[ken2esq]

Thanks, but I'm not trying to connect at 4k, and I am not trying to connect more than one external monitor.   

Optimally, I'd like to connect at the proper resolution for the external ultrawide, which would be 3440/1440 (or something like that), which is less than 4k. 

Connection one monitor whose resolution is LESS than the laptop itself (and thus within the capabilities of the computer) should be a piece of cake, but it just won't work.

Note, I plugged my 9 year old Sony Vaio into the monitor using same HDMI and it IMMEDIATELY displayed the image properly and clearly and without flicker, albeit at crappy resolution (that Sony maxes out at 1600:900).  The fact this new HP monitor is "plug & play" with this ancient Sony laptop, but not with my newish HP laptop is frickin' lame.

[ken2esq]

So, the HP Spectre works via HDMI using my Vizio TV as external monitor, very easily (plug & play).

Also, my 9 year old Sony Vaio works via HDMI to my new HP Envy 34" ultrawide, very easily (plug & play).

So we know the HDMI cable works and both the Spectre and the Envy Ultrawide work, just now with each other.

I have done all the troubleshooting I can think of.  I cannot think of any reason why connecting my HP Spectre via HDMI to this HP Envy Ultrawide leads to this endless loop of 

    black screen ... telling it it detects no signal ... then split second flicker of my desktop screen ... (repeat forever)

Note, in that split second flicker, I can see my computer display accurately reflected, so in that brief moment, the signal is going through just find.  but that's like  half a second every 20 seconds or so.  

Oh, during this cycle, my laptop is also going through a similar loop, wherein it recognizes there is another display connected, and then changes the display menu options as if I had unplugged or turned off the external monitor (which I did not do), and then it changes the display menu options again as if I had just plugged in the external monitor ... and repeat forever...  I mean, given that it thinks the monitor is being plugged in and unplugged over and over, I might think the HDMI cable had an issue except that it has been tested to connect my Sony to this monitor and to connect my Spectre to my Vizio TV, and it worked just fine.

Is there some fundamental incompatibility between the HP Specture laptop and the HP Envy ultrawide monitor?  Because I'm out of ideas.