Re: KVM switch: DVI-D, DVI-I or vga?
On 05/23/2015 12:26 PM, Bob Proulx wrote:
There is, in my opinion, a significant difference in visual quality
between the digital and analog display feeds.
I have one machine that can do dual-head. The primary display feed
starts as analog DVI-I, is adapted to VGA, goes into the VGA KVM, and
then goes into the VGA port of a consumer 22" LED LCD monitor. The
secondary display feed starts as DisplayPort (digital), is converted to
VGA, and then goes into the VGA port of an older 22" LCD monitor:
1. The primary image looks pretty good for desktop/ server stuff, but
shows its shortcomings with LCD monitor test images:
http://www.lagom.nl/lcd-test/
2. The secondary image is not as good as the primary, and the
flourescent backlight causes nasty flickering on some of the test images.
3. The motherboard and secondary monitor both have DVI-D ports. If I
change the secondary display feed to DVI-D (digital), I don't see *any*
difference in the image quality (including flickering).
4. Changing the secondary display feed back to analog, I don't see
*any* difference.
I can only conclude that there is no difference in image quality between
analog and digital display feeds.
But, there is a big difference in analog (VGA) vs. digital (DVI) KVM
product offerings and prices:
1. My IOGEAR 8-port VGA PS/2 KVM with cables (analog) is $159 on Amazon.
2. For comparison with the digital product, the 8-port VGA KVMP (adds
PS/2 or USB connectivity and two shared USB ports) is $364 with cables.
3. The DVI KVMP is $679.
While USB or PS/2 connectivity is nice, USB to PS/2 adapters are only
$14 each. I don't want or need shared USB peripherals.
David
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