Last month I bought a new Lenovo Yoga 920, which has an i7-8550U w/Intel 620 graphics and 2 USB-C/Thunderbolt 3 ports. The laptop is advertised as supporting DisplayPort Alternative Modes over USB-C.
Like many other owners of this laptop (Yoga 920 USB C to HDMI not working - Lenovo Community ), I've found that driving an external display over the UBS-C is very challenging. This creates real problems as this is a work machine for me and I need to be able to quickly change displays when meeting with clients, etc.
I've tried multiple adapters with external displays and, universally, I find that I an not able to make external displays work in a plug-n-play fashion. This is with the latest Lenovo provided bios & drivers, and Windows 10 home updates (fall creators).
I'm only able to successfully utilize external displays if I completely shut down the laptop. Unplug and plug-in the display adapter I want to use, make sure the external display is on, and then cold boot the machine. If I follow this scenario I'm able to consistently utilize various adapters for external displays. If I unplug the USB-C display adapter after successfully following this procedure, I'm not able to recover the display by plugging the adapter back in and need to reboot again from off in order to regain use of an external display. This is somewhat less than convenient and not what I would expect from a modern laptop. There are many individuals experiencing the same problem with this laptop. General consensus indicates there may be some model-specific driver issues creating this problem.
I wonder if anyone at Intel or in this forum can offer suggestions on what's happening to prevent external display recognition except at boot up and what resolution may entail as the issue has existed for several weeks with lots of discussion on Lenovo's forum with no resolution.
As described in the guidelines for Graphics questions here is further information about the issue and my specific device:
Answers (N/A if not applicable)
Provide a detailed description of the issue
USB-C display adapters do not initialize unless machine is booted from off. PnP for external display adapters does not work.
Please place an X to the right of the option showing how often you see this issue using specific steps. (Ex: 'Every few times a game is started it flickers.' <- This would be "Often")
Always (100%): X
Very Sporadic (<20%):
Brand and Model of the system.
Lenovo Yoga 920 (model 80Y7)
Hybrid or switchable graphics system?
No - embedded Intel 620
Make and model of any Displays that are used to see the issue (see note2 below).
EFP - Dell E2311H_Digital... issue is a consistent problem regardless of external displays requring an adapter to drive via DVI, HDMI, or VGA. Have not attempted TB3 display.
How much memory [RAM] in the system (see note2 below).
Provide any other hardware needed to replicate the issue.
Problem replicated with the following USB-C display adapters:
Plugable USBC-HDMI Adapter
CableCreation USB-C Type C to HDMI (4K2K@30Hz)+VGA Adapter
Lenovo forums indicate many others as well (See this thread: Yoga 920 USB C to HDMI not working - Lenovo Community )
Hardware Stepping (see note1 below).
Intel Display Adapter Hardware IDs
Operating System version (see note2 below).
MS Windows 10 Home
10.0.16299 Build 16299
VBIOS (video BIOS) version. This can be found in “information page” of CUI (right click on Desktop and select “Graphics Properties”.
Not sure - looked a few places and just saw 'Intel Video Bios". Screen shot from UHD Graphics Control Panel Info Center tab included below in case this has the necessary info.
Graphics Driver version; for both integrated Intel and 3rd party vendors (see note2 below).
SW or Apps version used to replicate the issue.
Single display, clone, or extended (see note2 below).
Problem occurs whether trying to clone or extend.
Display resolution & refresh rate setting of each display (see note2 below).
AC or DC mode, i.e. is power cable plugged in or not?
Problem occurs in when plugged in and when on battery.
How to repro
Please provide steps to replicate the issue. These steps are very crucial to finding the root cause and fix.
Only successful scenario (boot from cold)
What doesn't work
Attached are DispDiag dump files. One was run with the adapter working after a cold boot. The other is a dump after I unplugged the USBC end of the adapter while it was working and then plugged it back into the PC, effectively killing the ability to display on the external monitor until reboot.