Oaktech Posted June 20, 2022 Posted June 20, 2022 Ok, either my Google Fu, or my understanding is failing me here... I have a user who is swapping from a desktop with 3 monitors to a laptop with a dock and 3 monitors. We can't get the 3 monitors to work acceptably. The hardware is: An HP 840 G5 (https://support.hp.com/gb-en/document/c05903000#AbT7) A Dell WD19S USB-C dock (https://www.dell.com/support/manuals/en-uk/dell-wd19s-130w-dock/wd19s_user_guide/setup-of-external-monitors?guid=guid-2012dd96-1da9-4c70-ad24-0089516c9973&lang=en-us) 2x Lenovo L2251 monitors (https://www.ibm.com/common/ssi/rep_ca/5/877/ENUSZG09-0755/ENUSZG09-0755.PDF) Max: 1680x1050 1x Lenovo L215P (https://pcsupport.lenovo.com/us/en/products/monitors-and-projectors/lcd-monitors/l215p-wide-flat-panel-monitor) Max: 1920x1080 Also Connected to the Dock - Gigagbit Network, USB 2 KB, USB 2 Mouse, USB 2 Barcode Printer. I suspect it's a bandwidth issue, but I can't work out a configuration that works. Here's what's happening. Connect the dock to the laptop, lid open: *All monitors are detected, the L215 is detected as a 4th monitor and is disabled. *Built in display is 1920x1080 1xL2251 is connected at 1680x1050, 1xL2251 is connected at 1280x720 but can be changed manually to 1680x1050 Close the lid: *The L215 monitor is enabled but only connects at 800x600, this is the only resolution available. *1x L2251 is connected at 1680x1050 1x L2251 is connected at 1600x1000 this resolution can be changed down but not up and 1680x1050 disappears as an option. The latest graphics drivers are installed, the latest dock firmware is installed. Help.
chaplic Posted June 20, 2022 Posted June 20, 2022 If it's any consolation I've got the same dock and had similar dramas, over a variety of laptops. Ended up with one screen plugged directly into the laptop (USB C to Display port) which kinda sucks, but welcome to the world of USB-C hubs. 1
chazzy2501 Posted June 20, 2022 Posted June 20, 2022 In the BIOS of the similar HP 440 G7 there is a high resolution mode for the USBC. this will trade USB3.0 for 2.0 but offer more picture bandwidth. (the only way to run 4k60 on the G7) 1
Oaktech Posted June 20, 2022 Author Posted June 20, 2022 If it's any consolation I've got the same dock and had similar dramas, over a variety of laptops. Ended up with one screen plugged directly into the laptop (USB C to Display port) which kinda sucks, but welcome to the world of USB-C hubs. Yeah, this is a tester with 2 users to see if it's a feasible way of working for SLT and honestly, at the moment, after only 2 days trying, it's a no! The other user has the same equipment minus the 3rd L215 monitor and it's hit and miss whether the 2nd L2215 connects at 1280x720 or 1680x1050.
Oaktech Posted June 20, 2022 Author Posted June 20, 2022 In the BIOS of the similar HP 440 G7 there is a high resolution mode for the USBC. this will trade USB3.0 for 2.0 but offer more picture bandwidth. (the only way to run 4k60 on the G7) I'll check that out later - if I try faffing with this users desk setup again today after 2 hrs on Friday and an hour this morning, I think she will either cry, scream, brain me with the nearest heavy object, or all 3.
chazzy2501 Posted June 20, 2022 Posted June 20, 2022 https://support.hp.com/us-en/document/c06575423#:~:text=This%20can%20be%20performed%20by,DP%20a%20lot%20mode%20dock. 1
mavhc Posted June 20, 2022 Posted June 20, 2022 Those 3 monitors don't even add up to 1 4k display, so probably not maximum bandwidth limited. Update laptop bios and dock firmware for starters. How is each monitor connected? What if you use a connection on the laptop itself as a test? 1
Oaktech Posted June 20, 2022 Author Posted June 20, 2022 Those 3 monitors don't even add up to 1 4k display, so probably not maximum bandwidth limited. Update laptop bios and dock firmware for starters. How is each monitor connected? What if you use a connection on the laptop itself as a test? Laptop and dock are fully updated... the 2x 22" are both connected on DP the 21.5 is on HDMI, but it doesn't seem to matter what connection method I chose, one of the monitors is stuck at 800x600, it isn't always the same one. If I connect each to the laptop itself (1x HDMI out) I get the full resolution of the additional monitor.
Oaktech Posted June 20, 2022 Author Posted June 20, 2022 OK, I've just tried it, and the change of USB-C mode in BIOS makes no difference. Changing VRAM from 32mb (min) to 512mb (max) allows me to select 2 monitors at 1680x1050 and one at 1280x720, but the one at 1280x720@50hz is so flickery it's unusable. It doesn't allow a change to 60hz, so whilst on paper it's better, in use it's not. Anyone else?
chazzy2501 Posted June 20, 2022 Posted June 20, 2022 any chance that you are not using the USBC to USBC cable that is original to the dock? HB3 is a 12.5Gbps data rate.
mavhc Posted June 20, 2022 Posted June 20, 2022 Is there a utility to see the current usb-c connection specs, what bandwidth it negotiated, what protocols it supports? If you connect 1 monitor to the laptop hdmi and 2 on the dock, what happens?
Oaktech Posted June 20, 2022 Author Posted June 20, 2022 The dock is box-fresh and the cable is a replaceable module rather than an ordinary usb-c to c cable, so it seems highly unlikely it's that.
chazzy2501 Posted June 20, 2022 Posted June 20, 2022 well if you are in HB3 then 3x 1080p should be possible! (btw the docks cable as you mention is rather odd!) 1
Oaktech Posted June 20, 2022 Author Posted June 20, 2022 Is there a utility to see the current usb-c connection specs, what bandwidth it negotiated, what protocols it supports? If you connect 1 monitor to the laptop hdmi and 2 on the dock, what happens? I haven't found a utility yet. If I connect 2 on the dock and one on the on-board HDMI the following happens: With the lid open, one of the Dock monitors goes out 'maximum number of displays exceeded'. With the lid shut, the display connected to the on-board HDMI displays full 1920x1080 resolution, one of the dock monitors displays either 1280x720 or 800x600 (apparently randomly selected and changeable in settings), the other dock monitor displays the correct 1680x1050, making me think it is less the dock and more the machine.
chazzy2501 Posted June 20, 2022 Posted June 20, 2022 The dock relies on EDID and those older monitors only support version 2 (which should be fine btw) maybe they don't have original cables or have the EDID is disabled via the menu? 1
Oaktech Posted June 20, 2022 Author Posted June 20, 2022 The dock relies on EDID and those older monitors only support version 2 (which should be fine btw) maybe they don't have original cables or have the EDID is disabled via the menu? I'll check that out. One of the monitors connected on a DP has an error in intel graphics command about not being able to retrieve the full resolution list, and that is the one on the dock that randomly selects 1280x720, 800x600, 1600x100 1680x1050 depending on the scenario. I'll try another DP cable on that. It's not, however, the 3rd monitor on the dock that is stuck on 800x600 etc with though, that's connected via HDMI and shows a full list of modes and appears to be reporting its details correctly.
Oaktech Posted June 20, 2022 Author Posted June 20, 2022 Changed to a fresh DP cable and it now reports it's resolutions and ID correctly - but the behaviour of it choosing random resolutions each time something changes and the 3rd monitor being stuck at 800x600 has not changed.
Oaktech Posted June 21, 2022 Author Posted June 21, 2022 https://www.nirsoft.net/utils/dump_edid.html I'm on one of my other sites today, but I'll give it a go and let you know. Thanks for your help.
Oaktech Posted June 22, 2022 Author Posted June 22, 2022 https://www.nirsoft.net/utils/dump_edid.html The plot thickens - the EDID tool is reporting fine. All monitors EDID 1.3 and reporting OK. Might remove the monitor registry entries and let it have another go.
chazzy2501 Posted June 22, 2022 Posted June 22, 2022 (edited) Part of me is thinking that although those old monitors should work (L2251-1650x1050) they do not in this scenario. My lazy bones would just say that new 1080p monitors x2 would just work. The L2251 monitors must be over a decade old anyhow and are not display port native so you must be using an passive or active adaptor. (active is more common and cheaper?!?) EDIT: I was mistaken they are dp native but still old! Edited June 22, 2022 by chazzy2501
mavhc Posted June 22, 2022 Posted June 22, 2022 One option eliminated at least https://docs.microsoft.com/en-us/windows-hardware/drivers/debugger/usbview should show more details about usb devices 1
Oaktech Posted June 22, 2022 Author Posted June 22, 2022 (edited) Part of me is thinking that although those old monitors should work (L2251-1650x1050) they do not in this scenario. My lazy bones would just say that new 1080p monitors x2 would just work. The L2251 monitors must be over a decade old anyhow and are not display port native so you must be using an passive or active adaptor. (active is more common and cheaper?!?) They have DP ports and the EDID reports them as being digital DP-1.4 ? I've just tried 3 matching 2019 AOC monitors 2x DP and one HDMI. In the same positions, DP 1 gets full 1920x1080, DP 2 reports in Graphics settings as being 1920x1080 but is letterboxed and only comes out of letterbox if you unplug the HDMI monitor HDMI gets 1280x720 letterboxed but is fuzzy and can only be changed to 800x600. This is almost the same behaviour. I'm going to swap the user back to her desktop (The HP G800) and I'm going to try the dock on a Dell device and see if it's some sort of weird incompatibility between brands. All 6 monitors work as intended connected to an HP800G4 desktop with 2x DP and 1x HDMI or 2xDP and 1x VGA (We have devices that are the same base, but have different output options) and a Lenovo M720Q tiny with 1xVGA, 1x DP and 1x HDMI. I haven't tried mixing and matching AOC monitors with Lenovo monitors. I've changed all the cables now as well - 2x boxfresh DP cables and one different HDMI - no change. Edited June 22, 2022 by Oaktech
chazzy2501 Posted June 22, 2022 Posted June 22, 2022 (edited) FYI on the HP website the 840 G5 only supports 2 independent displays using the dock. not sure the dock is usbc though, so may not be relevant Edited June 22, 2022 by chazzy2501
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