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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?
- 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.
- Disconnect the DC power connection from the KVM should no longer have power.
- Wait at least 1 or 2 minutes.
- Connect the original power supply for the SV831DUSBU and ensure the power LED is illuminated.
- 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.
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.