This switch is the third one I tried and is well made. In my case I had 2 machines that switched fine, as well as an older desktop machine with a dual monitor graphics card that has an hdmi and a vga (15-pin) output connector. The vga output would not work when passed through the KVM switch. I believe this is a common issue with newer (hdmi based) KVM switches. VGA output is analog and even with a VGA to HDMI adapter it has a hard time with the conversion to HDMI as it passes through the switch. Direct-connected from the computer to the monitor worked, but not through the switch. All 3 switches I tried had this issue. This company was by far the most helpful and responded quickly to a support request via email, and promptly processed my return. If you have this issue the fix is to upgrade the graphics card on the machine to a different one that has HDMI and DVI outputs. Unless there is some HDMI-based KVM switch out there that handles this analog to digital conversion - I am zero for 3. The DVI to HDMI conversion works fine likely because both are digital signals to begin with. I upgraded to a card that had this, but *IMPORTANTLY* also had the same power requirements as my old card so I didn't have to upgrade the power supply.