I have an older Lenovo desktop running Windows 10. Its onboard graphics provide VGA and DisplayPort, while an old PCIe graphics card currently drives one 24-inch monitor over HDMI and has an unused DisplayPort output. I do not need gaming performance. The computer only has USB 2.0 ports and no USB-C.
My employer provided a Lenovo ThinkPad T16 Gen 4, which normally connects to two monitors through a USB-C docking station. I would like to use two monitors at home and switch both displays, along with a USB keyboard and mouse, between the desktop and the laptop dock using a KVM switch.
Would a dual-monitor KVM with separate video cables from both the desktop and the docking station be the simplest setup? Can I use adapters such as DisplayPort-to-HDMI for the desktop? Also, would adding a USB-C adapter or card to the old desktop and connecting it to a USB-C dock or KVM be a better approach?
2 Answers
Adding a USB-C adapter to the old computer is unlikely to solve this. A normal USB adapter cannot provide DisplayPort video, and the desktop's USB 2.0 ports are especially unsuitable for driving two displays. USB-C video from a modern laptop works because the laptop and dock support DisplayPort Alt Mode or Thunderbolt, not simply because the connector is USB-C.
The laptop dock can carry two displays over one USB-C cable because it is designed for that purpose. Cable length is not inherently a problem, but use cables within the dock and laptop manufacturer's specifications; active or overly long extension cables can cause intermittent display or USB issues. Keep the dock near the KVM and use regular certified display cables where possible.
A dual-monitor KVM with USB keyboard and mouse support is probably the cleanest solution. Connect both monitors to the KVM, connect the desktop's two video outputs to one input set, and connect the dock's two video outputs to the other. Then connect the keyboard and mouse to the KVM's USB peripheral ports.
For the desktop, DisplayPort-to-HDMI cables or passive adapters should work if the graphics outputs support them. Avoid relying on VGA unless necessary, since it is analog and will usually look worse. Check that the KVM supports the monitors' resolution and refresh rate on both computers, and make sure it has USB switching rather than only switching video.
That sounds more straightforward than trying to rebuild the older desktop around USB-C. I will check whether the KVM accepts the desktop's DisplayPort-to-HDMI connections and supports both monitors at their native resolution.
Since this is for office work rather than gaming, performance should not be a concern with a decent dock and KVM. The main things to verify are video resolution, USB compatibility, and whether the KVM reliably switches the laptop dock's display connections.