Dual Monitor DisplayPort KVM: Two PCs, Two Screens
Quick answer / TL;DR: Short answer: a dual monitor DisplayPort KVM switch has two DisplayPort inputs per computer, four in total, and two outputs to the monitors. Switching moves both screens and the USB peripherals together. It requires four DisplayPort cables plus USB links, and each path supports the resolution the switch specifies, commonly 4K60 on both screens. Check that the switch does not rely on MST to derive the second screen.
A splitter shares one link; a switch gives each device its own.Two computers and two monitors, with one keyboard and mouse, is a common office requirement and a demanding one for a switch. Four DisplayPort links must be routed without degrading any of them.
The port count on the box tells you what it does: four inputs and two outputs is the minimum for this job.
Port Count and Cabling
Each computer needs two DisplayPort connections to the switch, plus one USB connection for keyboard and mouse. That is three cables per computer before the monitors.
A switch advertising dual monitor support with only two inputs per computer is doing it correctly; one with a single input per computer is likely using MST and may not support independent modes.
| Configuration | Inputs | Outputs | Independent modes |
|---|
| True dual | 4 | 2 | yes |
| MST split | 2 | 2 | limited |
| Single plus split | 2 | 2 | mirrored |
| Dual with USB-C | 2 plus C | 2 | depends |
MST splits one DisplayPort link into two streams. It works, and it limits the total bandwidth shared between both screens.
Resolution and Bandwidth
Two 4K60 screens need about 25 Gbps of payload, which exceeds what a single DisplayPort 1.2 link provides. That is why true dual switches use two independent links.
Where the switch uses MST, two 4K60 screens are not possible and the specification will usually state 4K30 or 1440p instead.
- Two 1080p60: any design
- Two 1440p60: MST may suffice
- Two 4K60: two independent links
- Two 4K120: rarely supported
- Mixed sizes: independent links
Where the two monitors differ in resolution, independent links avoid forcing both to the lower mode.
USB and Peripheral Switching
The USB channel switches with the video, so the keyboard, mouse and any hub devices follow the selected computer.
Some switches provide a USB 3.0 hub, allowing a drive to be shared. Others provide USB 2.0 only, which is adequate for input devices.
Where a device must stay attached to one computer, use a port that is not switched or connect it directly rather than through the KVM.
Installation Order
Connect the monitors first, then one computer, and confirm both screens work before adding the second. Diagnosing four links at once is unnecessarily difficult.
Label every cable at both ends with the computer and the monitor it serves. Six identical DisplayPort cables are otherwise impossible to trace.
Test the switch with the computers running before dressing the cables. A unit that needs replacing is easier to remove before the installation is tidy.
Supported Modes in Practice
Where the monitors differ, set each to its native mode and confirm the switch preserves both. Some units force a common mode on both outputs.
Where one screen is portrait and the other landscape, the rotation is handled by the operating system and is preserved across switches only if EDID is stored.
Refresh rate mismatches between screens are handled independently on true dual models and forced to a common value on MST designs.
Cost and the Alternative
A true dual switch with four DisplayPort inputs costs more than two single switches, because it contains two independent switching paths.
Where the computers each have two outputs and the monitors have two inputs, switching inputs on both monitors and using software for the keyboard is a workable alternative at no hardware cost.
That arrangement fails where the monitors are not adjacent or where the operator cannot reach both, which is the case the switch solves.
Real-World Applications
Trader with two screens and two machines
A trading terminal and an analysis PC, both driving the same two screens with one keyboard.
Developer with a work and personal machine
Both computers on two monitors, switching at the press of a button without replugging anything.
Control room
Primary and secondary machines on duplicated displays, with the operator switching between them.
Design studio
A colour-critical screen and a reference screen, with the calibration applied at the monitor rather than the switch.
Action: Three Steps
First, count the DisplayPort outputs on each computer. Two each is the requirement for true dual.
Second, confirm the switch supports the resolution on both screens simultaneously.
Third, check whether the second screen is derived by MST, which limits bandwidth.
Related reading: HDMI DisplayPort KVM switches — blogs/news/hdmi-displayport-kvm-switch
Related reading: KVM extenders — blogs/news/kvm-extender
Related reading: Dual monitor KVM extenders — blogs/news/dual-monitor-kvm-extender
Standards and Verification
Multi-stream transport is defined by VESA within DisplayPort, allowing several displays on one link. Its use in a KVM switch constrains total bandwidth rather than adding capacity.
DisplayPort 1.4 provides 32.4 Gbps raw and 25.92 Gbps payload, which is the figure that determines whether two 4K60 screens fit on one link.
Verification: switch to each computer and confirm both monitors report their expected modes, then check the desktop layout is preserved. A layout that resets indicates the switch is not storing EDID per output.
Frequently Asked Questions
How many cables per PC?
Two DisplayPort plus one USB.
Does it support 4K60 on both?
On true dual models, yes.
What is MST?
One link carrying two displays, with shared bandwidth.
Can I share a drive?
Only if the switch has a USB 3.0 hub.
Why does the layout reset?
EDID is not stored per output.
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