At my workplace, I have a newer desktop with dual-monitor setup and an older desktop with one monitor. I have been using Maxivista, a multi-monitor software that converts my second pc’s monitor into a third monitor for my primary desktop. It does all this through the network without any extra cables required. They just released a new version this week.
If any of you have spare monitors and want to extend your primary pc’s monitor, this software is highly recommended. It also acts as a software KVM switch.