My Linux and Mac computers don't "see" the real monitor, can the KVM default be changed?


Viewsonic VS11449 monitor (Max resolution 1920 x 1200) But both machines say the monitor is a VGA G56x

Linux Mint XFCE 21.1 and Mac OS X 13.6 Both computers support at least 1920 x 1080 and have the latest drivers.

Linux box with ATI RV380 video card only lists 1152 x 864 and below

Mac box with Intel HD graphics 3000 on-board video only lists 1152 x 870 and 1024 x 768

Windows 8.1 box allows 1920 x 1080 and below

Hello @OldPete,

Thank you for posting your question on the Community.

I appreciate all of your device details too.

The specifications for the SV831DUSBU confirm that the 1920x1200 resolution of this ViewSonic monitor is compatible. I should not expect any issues from the monitor based on the specifications from ViewSonic.


Verify the connections between the monitor and the SV831DUSBU KVM, and ensure the cable and all the pins are in good condition and snugly seated in their sockets. Try a different VGA cable to connect the monitor to the KVM.

Use the recommended KVM console cables recommended between the computers and the KVM. The correct console cables for the SV831DUSBU are:

Check the specifications for any adapters or cables used with the KVM for correct resolution support.

Video source hardware

Based on the information I could find, the ATI RV380 does not support 1920x1080. The RV380 looks like a driver reference in Linux for the ATI X600 or similar. This ATI card seems to support a maximum of 1280x1024. The reported resolution of 1152x870 may be the maximum resolution supported by the graphics card and the monitor.

The Intel HD Graphics 3000 supports 1920x1200 based on details I found online. The lower-than-expected resolution with the Mac box with the Intel graphics could indicate an intermediate issue. Is this system connected to the KVM using an adapter? Check that the adapter does not have a maximum resolution below 1920 x 1200. Does the Mac box have a DisplayPort or mini DisplayPort connection? DisplayPort to VGA adapters are active adapters. Are there any other adapters or converters in use with the Mac box?

You mentioned that a Windows 8.1 box allows 1920 x 1080 resolutions and below. Is that on the SV831DUSBU? What sort of graphics adapter does the Windows 8.1 box have? Are there other computers that are used with the SV831DUSBU?


  1. For the KVM, a power cycle when troubleshooting and changing connections is a good troubleshooting step. Most of our hardware-based KVMs can draw power from the DC power source and the USB bus on the connected computers.

    To power cycle a hardware-based KVM, we must ensure there is no power to the KVM. Here are the steps:

    Disconnect the USB connectivity from the SV831DUSBU to each computer by disconnecting the console connection from KVM or the USB dongle at each computer.

  2. Disconnect the DC power connection from the KVM should no longer have power.
  3. Wait at least 1 or 2 minutes.
  4. Connect the original power supply for the SV831DUSBU and ensure the power LED is illuminated.
  5. Connect each computer back to the KVM in turn, and test as you go

These steps can help troubleshoot video or USB issues on our hardware-based KVMs.

Connect each computer to the ViewSonic monitor directly as a test. Bypassing the SV831DUSBU can help us to establish a baseline for performance.

Next Steps

We have gone over quite a bit of detail and asked several questions. With some more information, we can suggest other options or troubleshooting.

Please let us know if the steps and details above are helpful or if you have any new information. We can certainly take some time to review and help you find the best way forward.

Thank you,

David F

Hello David F.

Thank you for the insites you provided. I’ve been working on other projects - please excuse the long gap between posts! I am using StarTech cables in good condition. my VGA and DVI-D cables are also good. The Windows PC and the Linux PC do not have adaptors on the VGA cables the Mac has a mini-display port to DVI adaptor. I have tried all of the initial steps you mentioned without any change. I also replaced the video card in the Linux box with a PNY brand card with an Nvidia 520 chipset. The dual display feature works much better, but the resolution still maxes out at 1280 X 1024.

When I bypass the Starlink KVM, both computers identify the monitors correctly and allow 1920 X 1200. After I shut down, reinsert the KVM, and restart both computers go back to identifying the monitor as a VGA G56x monitor and downgrade the resolution.

I know that most of my old KVMs had a feature that “tricked” the computer into seeing a default, usually SVGA, monitor, generic keyboard and generic mouse on boot up, even if that KVM channel wasn’t selected. Back then, my monitors were SVGA so the 1280 X 1024 was fine. Since both computers have the same ID string, I have to believe the KVM is telling them that’s the monitor. The Windows box also says the monitor is a VGA G56x, but Windows is flexible (dumb?) enough that it lets me select video resolutions the monitor “can’t” display; Linux and MacOS aren’t as nice. So far, I have’nt been able to find a workaround.

Thank for listening!


Hello @OldPete,

Thank you for taking the time to isolate the resolution issues further with me. Don’t worry about the time gap. We are always happy to help!

I took some time this morning to review the manual for the SV831DUSBU a bit further. On page 8, I found a max resolution feature.

You can find a PDF copy of the manual on the Drivers & Downloads section of the product page. It is listed there as svx31dusbux_manual.pdf

Earlier in the manual, it describes how you can access the Hotkey and KVM menus:

Can you check these menus to see if there is a max resolution set? If so, does changing these settings help?

Please let us know if that information helps!

David F.

Thank you David F. !

After I opened up the max resolution, everything started working perfectly, even Linux options that were missing before! I appreciate the link to the manual, I remember doing a Google search for the manual before I came to the StatTech website, but failed to look for it after I got here. Sorry!

Once again, thank you for providing great customer service!


Hello @OldPete,

It is great to hear that the SV831DUSBU is working correctly for you now.

I am happy that we could help!

David F.