Dell UltraSharp U3415W has the same capability. Here's how it works, I would imagine other Dell monitors are similar.
There are four USB3.0 "A" ports you can use to plug USB devices into the USB hub built into the monitor. Three are on the same plate as the power/video connections (bottom backside of the monitor), and the fourth is out on the edge of the display at the back, like if you wanted to have an easier to reach place to plug a USB key.
There are two USB3.0 "B" ports to plug cables which would go to a computer. These are on the same plate as the power and video connections They're labeled "USB 1" and "USB 2"
In the menu for the monitor, you bind the USB ports to a video input. For example: "USB1 goes with DisplayPort" and "USB2 goes with HDMI"
Then you run the USB1 and DisplayPort cables to one computer, and the USB2 and HDMI cables to the other computer.
When you use the buttons on the monitor to select DisplayPort, your USB devices are automatically connected to the matching computer. When you change display input to HDMI, the USB hub automatically gets switched to the other computer at the same time.
It's quite slick -- But obviously you need to think about for example, USB storage, which doesn't want to be ejected uncleanly, which it will be if you switch display outputs without manually ejecting the USB key first.
"Is there some kind of DisplayPort only switch that I can just press a button and it'll switch it all over to the other machine?" You are describing a KVM switch, like this:http://ca.startech.com/Server-Management/KVM-Switches/2-Port-Dual-DisplayPort-USB-KVM-Switch-with-Audio-and-USB-20-Hub~SV231DPDDUA
– Ƭᴇcʜιᴇ007 – 2014-11-05T20:27:47.5331But if the USB is provided via the DisplayPort, I don't need a full KVM switch, just one that does DisplayPort :) – Michael Baldry – 2014-11-05T20:51:11.220
USB isn't carried over DP so you're going to need a separate USB connection from the monitor's USB-hub to the computer(s). – Ƭᴇcʜιᴇ007 – 2014-11-05T21:52:25.967
1
DisplayPort 1.2 carries USB http://superuser.com/questions/363649/can-displayport-carry-usb
– Michael Baldry – 2014-11-05T22:19:06.103Nice, I wasn't really aware of that AUX channel defined in that manner (just the Multi-Stream stuff). You video card may support it (it say it's DP 1.2, whether they actually used that feature of 1.2 and pumped USB through it would have to be tested). I'd be more concerned about that monitor you mention -- it's specs refers to the USB Hub and the specific USB upstream connector to connect the USB hub to the computer. Have you confirmed this monitor can do it? – Ƭᴇcʜιᴇ007 – 2014-11-05T22:33:38.517
There are DisplayPort 1.2-compatible KVMs out there as well: http://belkinbusiness.com/products/f1dn104p-belkin-advanced-secure-displayport-kvm-switch-4-port-plus. So again, you need a KVM, you just have to find the right one (and before you do it, asking for a product recommendation here at SU would be off-topic ;) ). But not only that, you have to hope that all manufacturers of the devices you choose, actually implemented a USB over DP solution in their "1.2" implementations.
– Ƭᴇcʜιᴇ007 – 2014-11-05T22:35:33.603Good question, I'd looked at the ports on the monitor and didn't see an upstream USB port so assumed it was via display port! Yes, I see a specification as something that must be implemented fully to claim your product supports it. Not implement half of it, but in the real world you are probably right :( – Michael Baldry – 2014-11-05T22:37:59.190
Maybe I'd just have to go for a DP and USB switch to keep things simple.. – Michael Baldry – 2014-11-05T22:39:03.130