I am evaluating the P15 mobile workstation with our Windows 10 build 1909 Enterprise image.  I am having a really bad issue with external monitors 'flickering', whether I connect the monitor to the Thunderbolt dock or directly into the HDMI port on the laptop.

I have done the following over the past 2 days:

• Installed the Nvidia control panel HSA from the store
• Tested 3 different monitors using different HDMI cables and different display cables
• Updated firmware on the dock and the laptop
• Run system update to ensure I have the latest version of Thinkpad Video Features (running version 26.21.14.4332)
• Installed current Windows patches
• Changed power settings to "maximize performance" both on battery and plugged-in
• Installed monitor drivers for the different monitors I am testing
• Tested both extended and duplicate desktop configurations
• Tested in and out of the dock (with cable plugged-into laptop HDMI port)

I am at a loss for what to try next.  I have seen monitor flickering issues in the past with P52 in the Thunderbolt dock but this is particularly bad.  It flickers about once every minute.  Sometimes I hear the Windows "device disconnect/reconnect" sounds when it happens, as if I am plugging-in a device.

If anybody has suggestions I'd love to hear them.

I’ve heard of some folks flickering issues being related to a setting with the Intel Graphics Command Center or whatever that’s called that manages the iGPU. Sorry I can’t recall the setting, either some dynamic brightness mode or power saving setting of some kind.

First, I do not own a P15/P17. So my comments are purely speculative. I know nothing firsthand about the machine.

You didn't mention what the graphics was in your P15, Quadro Tn or RTXn. But since it's a business machine I'll assume it's probably the lesser T1000 or T2000 which is present.

In past generations of Thinkpad laptops which included nVidia GPUs, there there was a delivered factory default "hybrid" (or "Optimus") graphics mode available via BIOS setting, which many users opted for. Primarily intended for a configuration that used minimal battery power and thus provided for maximum battery lifetime when running portable, it used Intel HD Graphics for the laptop screen most of the time. The nVidia GPU kicked in for certain programs and generally only when additional graphics horsepower was needed. This could be further tuned to support additional manually-forced use of the nVidia GPU through tweaks of nVidia Control Panel.  For external monitors connected through DP/HDMI/TB when running in "Optimus" mode, the nVidia GPU was always "in charge", including when using a dock. So you'd think since your issue concerns external displays that discussion of Intel HD Graphics and the laptop screen would be irrelevant. But...

Alternatively, you could set the BIOS to "discrete" mode which would essentially deactivate and disappear the built-in Intel HD Graphics and use the nVidia GPU for the laptop screen as well. Yes, this used more electricity, but the theory was that this wasn't of any concern if the laptop was almost or mostly plugged into wall power so that battery lifetime wasn't of concern.  In this "discrete" mode the nVidia GPU was used 100% for all graphics needs, for all programs and for internal as well as external displays. 

The README documentation for the graphics driver downloadable installer from Lenovo described the two configurations as possible:

I don't know if the P15 has a similar option in its BIOS configuration for display, but if possible you might investigate going to its "discrete" mode of operation, i.e. nVidia-only even for laptop screen. I know this shouldn't presumably have any effect on externally connected monitors (including through a dock), but it's worth at least an experiment.

Note that the Lenovo-provided "Thinkpad Video Features" graphics installer includes the driver for both Intel HD Graphics as well as for nVidia GPU, both included in the one package. They both get installed. And looking at the version designation it appears the nVidia piece of that driver package is actually nVidia 443.32. In theory this is the actual Lenovo-supported lab-certified version of the nVidia driver which should be perfectly functional and without defect for the P15.

However my own personal habit on my own older Thinkpads (P70 and W530) when "discrete" graphics mode was available is not only to configure the laptop to run in this 100% nVidia-only/always mode (including for the laptop screen, no matter whether plugged into wall power or running portable on battery) is also to use the latest nVidia retail graphics driver for my GPU downloaded from the nVidia site. These versions are definitely newer than the Lenovo-provided version packaged in its own downloadable installer, and have not been certified or guaranteed by Lenovo. Nevertheless my own approach is to use them instead of the Lenovo-provided older driver. My experience is that they have never caused me a problem, and I just wanted to be up-to-date with nVidia.

So in addition to trying "discrete" mode (if available), you might also try the retail nVidia driver for your Quadro GPU obtained from the nVidia driver download site. Note that the current nVidia driver version is 452.39, which is considerably newer than the Lenovo-provided 443.32.

Again, I really don't know if my comments are applicable to the P15 having never had my hands on one to research. And in theory the nVidia GPU is always supposed to handle externally connected displays. But my experience is that graphics performance of Lenovo laptops has always been "superior and stable" when running in "discrete" mode, and when using retail latest nVidia graphics driver for my laptop's nVidia GPU.

Thanks for the replies.  The P15 has the Nvidia Quadro T2000 video card.  

I went into the BIOS and I was able to switch to discrete mode as you suggested.  After it reboots I can see that the Intel display card no longer appears in Device Manger, just the Nvidia entry is there.  However, after I did that the laptop screen started flickering about every 30 seconds without any dock or external monitor connected.  I had to switch it back to Hybrid to get the laptop display to work correctly.  Once I switched it back I also tried disabling the Intel display adapter in Device Manager but the flickering continued.

Next I installed Intel Graphics Command Center from the MS Store and turned-off all power-related settings:

Turned off Display Power Savings on battery

Turned off Panel Self Refresh on battery

Turned off Panel Self Refresh in the PLUGGED IN tab

Turned off "Brighten video"

I didn't see any other auto power or brightness settings in the app.  Unfortunately it didn't help.

Next I downloaded the latest NVidia driver (452.39) for the T2000 card.  It updated my Nvidia driver from version 26.21.14.4332 to version 27.21.14.5239.  After a reboot it is still flickering.

I appreciate the replies, if anyone has other ideas please let me know.

Sorry for your troubles :-/

My only other idea is a loose or faulty display cable. What you’re describing sounds like a software issue, but it seems you’ve pretty thoroughly tried a lot of options for working around it. I’m afraid I’m stumped.

Sure sounds like a flaky defective nVidia GPU, perhaps happening when it heats up a bit from use. Can't imagine a "cold solder" or other board-related issue.

When the nVidia was being used for external displays only (i.e. with "hybrid" still in effect) the external displays flickered. And the Intel-controlled laptop screen was fine. Then when you went to "discrete" which includes the laptop screen under nVidia control, well now the laptop screen [as well as the external display still?] also exhibited the flicker.

This seems to point to the nVidia GPU as the actual culprit, not driver version or other software. And it has nothing to do with an HDMI connection, since the laptop screen isn't connected that way.

Time for a warranty ticket with Lenovo I would suggest, possibly replacing the motherboard/GPU or possibly getting a replacement P15. That's what warranty is for.

Sounds like hardware issue to me.

Good catch on the external vs internal display detail.

FWIW the Intel Graphics setting I was thinking of is called Panel Self Refresh, which can cause flickering with panels that don't sync properly; here's an example reference: https://www.reddit.com/r/thinkpad/comments/jb50zf/thoughts_on_the_p15_gen_1_hmmm/g8u0ufd/?utm_source=reddit&utm_medium=web2x&context=3

I had the motherboard replaced and the symptom did not go away.  I've done a LOT of trial and error since then and I have come to realize that my external monitor is briefly turning off and on because Device Manager is refreshing (collapsing and expanding).  When it happens, I hear the Windows sound indicating that a device was removed or added (as if I unplugged a USB device).  This happens once or twice every minute for about 30 minutes and then stops.  Each time it happens my monitor flashes off and on for a few seconds...

If I go into Device Manager under SYSTEM DEVICES there is a device called "Remote Desktop USB hub".  If I disable and then uninstall that device and then reboot, the symptom stops (Device Manager stops refreshing and the monitor stays on without flashing).  However, Windows 10 self-repairs and reinstalls the Remote Desktop USB hub device and then tells me I need to reboot to finish setting up the device.  After a reboot, the device is enabled and Device Manager starts refreshing again, and the monitor starts flashing again.

So it appears that my P15 has some sort of conflict with that device (Remote Desktop USB hub).  Remote Desktop USB hub is on all of our other Lenovo devices including P50, P51, P52, P53 and they all work fine with external monitors on the same OS build.

Does anyone know how I can narrow-down the conflict?  Alternatively, is there a way I can prevent Windows 10 from automatically reinstalling the Remote Desktop USB hub after I uninstall it?

Thanks

If you stop and disable FirmwareSwitchService from Windows Services, it "fixes" the problem. No idea why (still looking into it), but at least it's not flickering.