How come DVI KVM's are 10x more expensive than VGA KVMs?

Question

KVM switches for VGA displays vs for DVI displays: From examining prices both these days and a couple of times over the past year or two, I've noticed that, generally, 2-machine KVM switches, with USB ports for keyboard and mouse, are about an order-of-magnitude, 10x or so, more expensive for DVI displays.

DVI is newer and more complex technology, so maybe the hardware for it is a bit more expensive, but were talking about a passive component which doesn't do any DAC, just switches wires. So where does the 10x price difference come from?

I realize that DVI-based KVMs are newer on the market. However, DVI has been around for more than a decade already; and while VGA KVMs have been around for longer, they used to have PS/2 connectors rather than USB ones. So the age difference doesn't explain such a price gap. Also, I'm not comparing apples and oranges w.r.t. audio connector switching, or massive metal vs lightweight plastic boxes.

Answer 1

Your assumption that the KVM is a passive component is wrong. Even with VGA, the KVM has to correctly manage access to the EDID in the monitor. The video sources cannot read the monitor EDID simultaneously. However the video signals are totally analog so once the sources know what format to send, they can be switched in and out as needed.

DVI (the digital part) is not just unidirectional signals, there is a whole protocol that requires timing synchronisation on both sides of a link. On top of that is HDCP where encryption keys need to be synchronised.

There might be some clever trickery to reset the links every time the video source is switched, but I think the normal way to do this is to decode the video data in the KVM, then re-encode for the monitor. This means the links to the monitor and video sources needn't be reset all the time. However, to do this you need a rather powerful FPGA (or bespoke ASIC) to at least maintain multiple input links and to forward the right video data to the output links.

In addition to all that, I'm sure there's a lot of testing to iron out quirks in different devices. These are probably widely known for VGA, but not so much for DVI.