On Sun, Jan 22, 2012 at 10:54 AM, Mark Knecht <markkne...@gmail.com> wrote: > I've seen reports for years about folks having problems with some KVMs > under Linux. I've never personally had one myself. However I've been > helping a Windows friend break his Redmond addiction over the last few > months using Gentoo. He has a nice 3 monitor KDE-based system that's > been working fine but there was one monitor that refused to set up > with the right resolution. We left it alone for a long time as it was > usable but finally yesterday got together to figure out what was > happening. From the title it should be clear that the problem was a > KVM hooked to that one monitor. Removing the KVM completely solved the > problem. > > Now, what I'm wondering is why this same video card/KVM/monitor > combination which apparently worked in Windows should have any > problems in Linux? Anyone know why? > > In the spirit of full discloser I don't really know that this > _specific_ video card was tested in Windows, but he owns multiple > NVidia 8400GS cards and it's my understanding that other 8400GS cards > did work with this KVM & monitor, so unless it's this specific card > having a defect, or even being just a bit weak in some way, it would > seem to be the insertion of the KVM itself that upset things. > > Looking at the monitor's specs/requirements for running the higher > resolutions it uses, as should not be a surprise, higher frequencies > to do higher resolutions. If the KVM was filtering those a bit then > it's possible things wouldn't work, but that doesn't explain why it > did work in Windows. > > Basically, I looked around in Google for anyone that had real info > about why this problem occurs, couldn't find any that made sense, and > am wondering how to choose a KVM that's going to work out of the box > short of asking for model numbers, etc.
I assume these are VGA displays? I've noticed that the CRTs attached to my Win7 box at work don't get configured for the highest refresh rate unless I force it. Also, I've noticed it decide that '1280x1024' is the 'recommended' resolution for my displays, though they'll do 1600x1200@60Hz. It could just be a matter of Windows using 75Hz instead of 85Hz, or 60Hz instead of 75Hz. -- :wq
