IOGEAR4-Port DisplayPort KVMP Switch - 4K 60Hz - 2-Port USB 3.1 Hub 5Gbps - Keyboard Mouse Input - 7.1 HD Audio - Front Panel Selector - TAA Compliant - Mac/Win - GCS1934

I think this is my 5th IOGear KVM of the pricey variety in the past 15 years. They've all performed well. Only one had a power supply give out. Since getting a Dell U3219Q I wanted one of these because my existing one could not handle 4k and at the time they didn't have one that supported 60hz. Then this was born and I hesitated for over a year because of the price. So I used the HDMI and DP ports on the monitor and switched screens using the monitor software. Then used an even older IOGear KVM to manage the KB/mouse.Adding a laptop allowed me to finally justify the costs. BUT - turns out there's ONE catch in my particular scenario. Obviously this switch is all DP but my laptop only has HDMI. Simple enough I though, I have a 4k HDMI -> DP cable I'd gotten at BB on a whim one day. This just did not work at all. Could not get the laptop to display anything on the U3219Q.So the KVM is connected to the DP on the monitor. I just ran an HDMI cable from the laptop to the monitor and a USB cable from the laptop to the KVM. The monitor is smart enough to hunt for a signal when one goes missing. So when I switch between the desktops connected via DP and the laptop, it works just fine. Switching away from a desktop kills the DP connection between it and the monitor - so the monitor hunts around, sees the HDMI signal, and displays the laptops screen.That cable that didn't work is rated 4k so I'm not really sure why HDMI -> DP didn't work. Maybe it's something to do with the laptop, I have no idea. My workaround works just fine so I'm not motivated to figure out where the problem lies. I did use a similar adapter (short, not a full cable) recently to connect my prior HDMI KVM to a newer desktop that only had DP. That worked. Maybe I'll get another one of those and try it. If that works I'll post an update.I've used the Scroll-lock + number method for years to switch between devices. I can't remember if that's something I had to enable in the past or not. Really liked that this one supported that out of the box. Just put the manual away after that.<update> I just learned something. Though no fault of IOGEAR, apparently some graphics cards don't behave well in a Windows environment when using a DP connection. It's nothing terrible, just terribly inconvenient if you always have allot of applications running that are not minimized and you're switching back and forth. For me, it's random - but sometimes when I switch, all of the windows that were open get resized (shrunk) on the machine I'm switching TOO. According to searches, this is widely known but new to me. If your running Windows and your monitor and machines all have HDMI connections, get the GCS1934H. SAME switch, just HDMI instead of DP. I'd never heard of this quirk with DP connections. IOGEAR support was lightning fast to reply and lay out all the details.

I'm using a Dell 27 Ultra HD 4k Monitor - P2715Q at 3840x2160 @ 60Hz. I love the monitor. I have a windows 10 desktop, a linux desktop, and a windows 10 laptop. Obviously, all these connections are display port (out of the dock for the laptop). I'm not using the audio features of the KVM switch so I can't comment on those. My USB keyboard and wireless mouse are typical mid-range, nothing special. Can't comment on the problems people have had with high-end keyboards. Mine work perfectly. I use the double scroll lock protocol to change computers.This is an expensive product, so you'd want it to work perfectly. It doesn't quite. However, with a couple of tweaks, it's nearly perfect.I've had help from IOgear support and am running new firmware that hasn't been released yet. It's called GCS1932_1934_TEST_170519. You may want to see if the work-arounds I mention below solve your problem before working through the layers of IOgear support to get to someone who knows about this firmware and will give it to you. I got the new firmware before I changed the power on detection setting. I can't tell whether I needed the firmware, but they did seem to think it would be helpful for my problems. My problems were always about what happens when a computer powers down a display for energy savings and the KVM doesn't restore the display properly when the computer powers it back up.If all your screens are always powered (you don't have power down on timeout for energy savings), then it does work perfectly as far as I can tell. Once you enable monitor energy saving power down, you get into trouble when the KVM automatically switches to the next computer when the computer powers down the monitor. There is a setting you can change for that (you will have to read the manual to find the procedure to switch this setting to off -- it is called "power on detection" under "advanced settings"). Disable that "auto-switch on power down" and you're mostly home.My remaining problm is this. My windows 10 laptop and the KVM don't agree with each other when I switch away and then back. Sometimes the monitor just goes into low power mode as if the laptop isn't driving, but if I check the display settings on the laptop's built-in screen, I can see that the laptop thinks it is driving the display. It turns out that there is an easy work-around for this case (two actually). Either 1) disconnect and reconnect the displayport cable on the monitor (between monitor and KVM, not between laptop and KVM) and the KVM initializes correctly and the the laptop display returns, or 2) using the monitor settings, switch to another input (e.g., HDMI) and immediately switch back, and the same exact thing happens -- the KVM initializes the connection correctly and you have the laptop display again. I can tell the laptop thought it was driving the large display the whole time because the windows and desktop icons haven't been moved the way they would be if I actually pulled the displayport connection from the back of the laptop. Windows responds to the screen size by moving things around.As an added note, if the laptop is set to power down the display after some time for energy savings (as mine is), and you switch away from the laptop and don't switch back until that time has passed (so the laptop will have powered off the monitor it thinks it is connected to), then switching back to the laptop always works correctly (with a minor delay for some reason). The only real problem is switching to the laptop when it thinks the monitor is powered on and you have actually been connected to a different computer using the KVM. That's when I use the trick of switching input source on my monitor to HDMI and back to DP (using monitor control buttons) and the screen comes back up.I do not have the problem with the desktops, but only once I disabled the auto-switch feature (in other words, I did have problems before that, possibly related to the original firmware).My screen is gorgeous from all three sources and I'm very happy with the KVM in general.All the cables needed (even audio) came with it and are all very decent quality.This KVM is expensive but less expensive than two other choices out there and who knows what quirks they would have. The others cost the same or more and don't come with cables so your total cost can be a lot more.