For the grief and anguish getting this to work I really want to give a 3 or maybe a 4 star rating at best. But I have to admit to contributing to the problems I had myself. But the thing is, at the end of the day this box works as advertised. Make sure you read the scant literature that's available, twice or maybe even thrice. I looked and looked but I couldn't find the manual for this box on Startech's website. There was a manual for the 4 port KVM and that was for the all DVI port model. A simple cabling diagram for this exact box would have saved a lot of time and gnashing of teeth.The manual only covers the SV431DDVDUA in great detail, including features that are not available on the two port model.This unit, SV231DDVDUA is only mentioned in passing, no pictures, no diagrams, no nothing.I was very close to sending it back.This KVM is for a vender certification lab project that I set up in my home.I purchased this unit to switch between two computers, one with only VGA, the other with only DVI outputs.Because the computers had different video outputs was the reason I thought this KVM would be what I needed.In the end it works.I will not cover all of the cabling trial and errors I went through so I'll skip to the chase and tell you what worked for me.The computer with the DVI video had a fairly high end dual DVI & Display port card.I replaced the card with a very low end card that had a single DVI port and a single VGA port.I don't even know why I still had this card. I should have thrown it out years ago.So, to you electronics pack rats...old does not mean not useful.In the manual under "System Requirements" does say: DVI and VGA enabled computer system/video card.While there may be other ways to get this box to work, it would not work for me until at least one of the computers had a dual video card.Once you understand that, then this box is all that and a bag of chips.I would rather have given 4.5 stars, but there are no half stars available so I'll give 5 stars.StarTech: how about including an accurate manual/user's guide of THIS box on your website that includes a cabling diagram.StarTech: how about making this series of KVMs a little larger or arranging the DVI connectors so that two DVI connectors can be plugged into the box next to each other. Right now the connectors are so close you cannot get two connectors side-by-side.Lastly, because this ends well I'll be generous and include a plug for another StarTech product.The certification lab project requires me to connect to the console ports of routers, switches, and firewalls.Most modern desktops don't come with a serial port/connector any more.I bought a StarTech PCI2S550 2 port PCI RS232 Serial Adapter and it works great.Once again the documentation is less than desirable and the ports are not labeled, so you have to be a little persistent.Windows recognized the card and the 2 ports without needing to use the included drivers disk.I purchased this KVM specifically because it was able to handle VGA and DVI inputs and because I have 3 different PCs that utilize 3 different video configurations:1) Has dual VGA outputs (older PC)2) Work laptop has 1 DVI and 1 VGA3) Home desktop has dual DVI***I'm inheriting a MAC that has a DVI out, haven't tested this yet, but I'll be interested to see how the keyboard functions considering the keys are different on a MACOverall the device works well with the multiple configurations. I had to be somewhat creative with how I connected everything. Fortunately my monitors support the DVI or VGA connection and the KVM has a single DVI and single VGA connection for each PC I need it to support. For the PC that had dual DVI connections I had one monitor connected to the KVM and then the other monitor I actually ran the DVI cable to the PC and used the button on the monitor to switch back and forth. I do the same thing for the dual VGA configuration. Obviously for the laptop that is DVI/VGA I just use the device as is.A couple of minor things that honestly I don't fault the device/manufacturer for is how it operates before the system boots to windows (haven't tried this with Linux systems, but it would likely work). My company has a security software (I believe it's disk encryption security) that requires to enter your password before booting into windows. The keyboard works, however I do have to press the keys twice when entering the password. For example if the password is 123, you'd have to enter 112233 for it to enter 123.The other item I've read about in other reviews is the occasional power flicker, where the device beeps and your monitors flicker. While this is a bit startling at first, it's actually kind of rare and for the convenience I get with having the device it's a very minor downside that I'm willing to accept. Frankly you are taking multiple inputs with varying signals, so the fact that the device works as well as it does is good enough for me.The only con I would mention is the price. I think I paid around $230 which is pricy for a KVM. But like I mentioned above, most KVMs only handle one or the other (VGA / DVI).One last pro is StarTech support. Prior to purchasing the device I contacted them via live chat and was able to explain the configuration I had and confirm that the device would meet my requirements.After trying out a couple of KVM switches, this is the one that met my requirement 100%. My setup is a bit unusual in that it involves both VGA (from a server computer) and DVI-D (from desktop computer). The experience with different KVM switches - including Would be great if this worked reliably, unfortunately it does not, it radomly stops working on one or more channels. The only remedy suggested by their tech support is to completely power down and unplug everything and then start from scratch.....not a very practical resolution.What an unbelievably idiotic design. It's not physically possible to plug the DVI connections in next to each other - there simply isn't enough space. I am using StarTech cables specifically bought because they were the same make...I got this product so i could use my macbook as a desktop pc without having t faff about unplugging monitor cables, mouse, keyboard etc.. from my desktop windows computer.This product does exactly what it says it does. nothing to install just easy plug and play. only downside is that it seems a little pricey for a box that just switches between two pc's.great - a bit fiddly getting the right cables sorted out but perfect - one touch and I can switch easily between different computers