Poor multi-monitor performance using Dell Wyse 7020 Windows 10 IoT with VMware Horizon View 6.x to 7.x

This is a follow up to a previous post I wrote about poor VMware Horizon View video, keyboard and mouse performance when adding a 3^rd monitor to the Dell Wyse 7020 Windows 10 IoT thin client:

Adding a 3rd monitor to a Dell Wyse Z90QQ10 thin client connecting to a VMware Horizon View 6.2 virtual desktop causes slow video performance with mouse movement and typing delays

http://terenceluk.blogspot.com/2018/04/adding-3rd-monitor-to-dell-wyse-z90qq10.html

The poor performance issue began affecting our Microsoft Windows 2016 RDS services, which escalated the priority so I was finally able to take 2 days to troubleshoot the problem. I had also opened up a ticket with VMware and Dell prior to beginning troubleshooting the issue myself and the VMware EUC engineering said this was likely a Dell Wyse issue since it does not happen on a full thick PC while Dell never got back to me at all after a ticket was opened. I’ve never been impressed with Dell support for the Wyse devices but figured I’d give them a try but they have yet to call me days after the ticket was opened and I don’t have much confidence that I would receive a call back soon.

Before I begin, the following are the environment details:

Hardware

Thin Client: Dell Wyse Z90QQ10 Thin Client

Operation System: Windows 10 Enterprise 2015 LTSB

Monitors: 3 x Dell P2414Hb (1920 x 1080) and 3 x Dell U2417H (1920 x 1080)

View Horizon Client: VMware Horizon View Client 4.8.0 build-8547331

Troubleshooting

The first item I looked at the start of the troubleshooting was the PCoIP Client Session Variables configuration provided by VMware to apply to the Horizon View Client and in particular the Configure PCoIP client image cache size policy and Configure the PCoIP session bandwidth floor settings:

Both of these settings did not help with the problem so I moved on to upgrading the VDI’s virtual machine version (no improvement), increasing resources (no improvement) then reviewing the drivers available for the two video cards in the thin client but noticed that there was an 2 month newer update for the AMD Radeon HD 8330E but no update for the AMD Radeon E6460:

Realizing I’m not going to have much luck with the drivers or the Horizon View Client application tweaking, I started reviewing the display output connections of the thin client:

After trying different combinations to connect the 3 monitors, I concluded that the degrade in performance happens when both of the video cards are used. Independently using the video cards to display 2 monitors at a time was fine but using 1 output connector from each video card for 2 monitors degraded performance immediately. Having ran out of ideas, I decided to review the specifications to see if I had missed something:

https://www.dell.com/en-us/work/shop/wyse-endpoints-and-software/wyse-7000-series-thin-clients-high-performance-virtual-desktop/spd/wyse-z-class

What I immediately noticed was that the thin client actually supported 6 displays as indicated under the Display specifications:

Wyse 7020
DisplayPort: 2560 x 1600 @32bpp
Dual DisplayPort: 2560 x 1600 @32bpp
DVI-I: 1920 x 1200 @32bpp
Dual Display: 1920 x 1200 @32bpp
Four Displays (DVI & DisplayPort): (1) 1920x1200@32bpp, (3) 2560x1600 @32bpp
Four Displays (DisplayPort daisy-chain): 3840x2160@32bpp
Six Displays (DisplayPort daisy-chain): 2560x1600@32bpp

I have to admit that I don’t really follow the advancements of monitor outputs so I was unfamiliar with DisplayPort daisy-chain but taking it literally made me realize that I could potentially connect more than 2 monitors to the same video card. The Dell P2414Hb (1920 x 1080)

monitors we had in the office did not support daisy chaining so we ended up purchasing 3 x Dell U2417H (1920 x 1080) to test this capability and I immediately noticed that daisy chaining 3 monitors to the AMD Radeon HD 8330E video card provided optimal performance in Horizon View. I then went and tried to the do the same with the AMD Radeon E6460 and received an error indicating it only supported 2 monitors via a single daisy chained display port.

It was a bit absurd to find that this was the problem and I could not find any information about this anywhere on the internet so I hope this post would help anyone who may encounter the same problem. Below is a photo of the Dell Wyse 7020 back panel with the video cards labeled and a table of the test results:

AMD Radeon E6460

Port	Connection	Monitors	Resolution	Performance Results
Display Port	Daisy-Chain DP	2	1920 x 1080	Poor with mouse delays
Display Port	Daisy-Chain DP	3	1920 x 1080	Unsupported as only a maximum of 2 monitors is supported
DVI and Display Port	Direct connection	2 (1 on DP and 1 on DVI)	1920 x 1080	Good as expected

AMD Radeon HD 8330E

Port	Connection	Monitors	Resolution	Performance Results
Display Port	Daisy-Chain DP	2	1920 x 1080	Good
Display Port	Daisy-Chain DP	3	1920 x 1080	Good
Display Port	Daisy-Chain DP	4	1920 x 1080	Good
Display Port	Daisy-Chain DP	4 (1 on DP and 3 on other DP)	1920 x 1080	Good

**Any combination of mixing the AMD Radeon E6460 and HD 8330E resulted in poor performance and would generated the following low on memory message for the VMware Remote MKS service:

Close programs to prevent information loss

Your computer is low on memory. Save your files and close these programs:

VMware Remote MKS