Question KVM USB keyboard/mouse disconnect issue

dorkshoei

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Mar 15, 2017
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10,510
I just got a new 4k@60hz monitor which required I replace my existing IOGear DVI kvm switch which has worked great.

I wasn't finding a lot of 4k kvms at a reasonable price so I bought this GREATHTEK on Amazon https://a.co/d/96bq1GQ

It has a major deficiency, it disconnects the USB keyboard/mouse when you switch. In Linux you can see this in dmesg and in Windows it causes the device-disconnect device-connect sounds to play every time you switch which is annoying.

I guess some kvm switches (like my old IOGear) maintain a dummy USB connection to disconnected machines to avoid this issue.

- I don't want to disable USB connect sounds globally in Windows 10. Is there any way to disable it for just a subset of devices or a specific USB port?

- Anyone know of. 4-port 4k@60hz kvm switch that maintains USB connectivity on switching? I'm not sure there is an official term for this feature so it can be hard to evaluate products.
 

dorkshoei

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Mar 15, 2017
19
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10,510
I have been using the 2-port version of this KVM and have been very happy with its performance. I do not have the "disconnect issue" you described.


Thanks I'd seen this brand when reviewing but I bought the GREATHTEK as it had a slightly better average review rating lol.

I think https://a.co/d/2ao3sNP is the 4 port HDMI version. It mentions "Support keyboard and mouse pass through mode to improve mouse and keyboard compatibility" which may be the feature I'm looking for.
 

dorkshoei

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Mar 15, 2017
19
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10,510
As stated earlier, I have the 2-port DP version and the pass-through concern you stated earlier is not an issue. I would expect the HDMI version to have the same feature/capability.

I understand. I'll ask the seller to be 100% sure before ordering a second. Else I'm looking at returning two
 

dorkshoei

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Mar 15, 2017
19
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10,510
So I bought the TESmart. https://www.amazon.com/dp/B08124CPLM

It doesn't have the USB disconnect issue that the GREATHTEK had.

All was great initially.

I was using it with:
  • Port 1. old PCI motherboard with Radeon HD5450, output capped at 1080p
  • Port 2. Dell Precision 3440 with integrated UHD graphics 630. Amazon active DisplayPort to HDMI adapter, output 4K@60hz

I upgraded Port 1 to an MSI B550M PRO-VDH with an AMD Ryzen 5600G cpu, integrated graphics, output 4K (not sure how to determine HZ).

The issue is that the monitor (Samsung UR55, port HDMI1) every 30 or so minutes will just stand randomly blanking when connected to Port1. It will turn on/off about 4-5 times over a 30 second period, then stabilize.

If I disconnect the cable
 

dorkshoei

Honorable
Mar 15, 2017
19
0
10,510
So I bought the TESmart. https://www.amazon.com/dp/B08124CPLM

It doesn't have the USB disconnect issue that the GREATHTEK had.

All was great initially.

I was using it with:
  • Port 1. old PCI motherboard with Radeon HD5450, hdmi output 1080p (max for the card)
  • Port 2. Dell Precision 3440 with integrated UHD graphics 630. Amazon active DisplayPort to HDMI adapter, output 4K@60hz
However I started having issues after I upgraded the PC on Port 1 to an MSI B550M PRO-VDH motherboard with an AMD Ryzen 5600G cpu, integrated graphics, output 4K (not sure how to determine HZ).

The issue is that the monitor (Samsung UR55) every 30 or so minutes will just stand randomly blanking if it is connected to Port1. It will turn on/off about 4-5 times over a 20 second period, then stabilize. Doesn't occur with the Dell on Port2.

I tried a different hdmi cable and connecting the to Port4 rather than Port1. No difference.

If I bypass KVM switch and connect the machine directly to the monitor the issue does not occur.

I updated the graphics driver from MS version to AMD (MS was was only 1 release older). No difference.

Anyone have any suggestions. TESmart "tech support" is not really interested.
 

dorkshoei

Honorable
Mar 15, 2017
19
0
10,510
This has not happened with my DP version. Will do some googling and see if there are any suggestions.

I didn't realize the new MSI motherboard had a full size DP output as well as HDMI. I can buy an DP->HDMI adapter and see it if changes the behavior. I can't borrow the adapter from the Dell as that is a dedicated mini-DP to HDMI cable.

The monitor has DP input (plus 2 HDMI) so another option is to try exchanging the switch for the DP version you have.
 

dorkshoei

Honorable
Mar 15, 2017
19
0
10,510
@COLGeek so I got a Display Port to HDMI active adapter. 4K@60hz

If I connect it to the Display Port on the B550M I only get 1920x1080 (through KVM or direct to monitor). If I connect the adapter to my Dell system (mini-DP->DP adapter, then the above adapter, I get 4K@60hz).

MSI manual says:

∙∙1x DisplayPort, supports a maximum resolution of 4096x2160 @60Hz*
∙∙1x HDMI 2.1 port, supports a maximum resolution of 4096x2160 @60Hz/*

* Available for the processor with integrated graphics.
** Graphics specifications may vary depending on the CPU installed.

I have the latest BIOS. MSI are on vacation until new year.

Hmmn. I was hoping, since it appears to be an issue where the KVM doesn't quite like the B550M HDMI signal that it might prefer the signal from the active dp->hdmi adapter.