<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><BR><DIV><DIV>On Jun 8, 2006, at 7:56 AM, Will Constable wrote:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"> <DIV class="Section1"><P class="MsoNormal"><SPAN style="font-size:10.0pt;font-family:Arial;color:navy"><O:P> </O:P></SPAN></P><P class="MsoNormal"><SPAN style="font-size:10.0pt;font-family:Arial;color:navy">Yea- my current setup is s-video via homemade cable—40 ft of cat 5 with s-video and audio connectors at each end, running through the walls- I know, sounds like a recipe for disaster. But my laptop drives a <I>perfect</I> signal from one end to the other while I have this problem with the myth box. So I am thinking its either the card or the settings/driver.. I have been using nvidia instead of nv, but have not tried a whole lot of options for resolution on my vga port. I was thinking it would be good to try identical settings and do a clone, but I don’t know how to write xorg.conf for that—mine does dual screens not using xinerama. It does occur to me though, that the setup I have upstairs is 1024x768 on s-video and 1600x1200 on vga—while the monitor downstairs cant run 1600, maybe this setting would make the interference go away. Do you know how to set up xorg for clone? Also, can I set the horizsync and vertrefresh of my vga monitor to match what my tv uses, or might this cause a problem?<O:P></O:P></SPAN></P><P class="MsoNormal"><SPAN style="font-size:10.0pt;font-family:Arial;color:navy"><O:P> </O:P></SPAN></P><P class="MsoNormal"><SPAN style="font-size:10.0pt;font-family:Arial;color:navy"><O:P> </O:P></SPAN></P></DIV></BLOCKQUOTE></DIV><BR class="khtml-block-placeholder"><DIV>Some things to try:</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Since you get a good signal with your laptop, try moving your TV set next to your Myth box and connecting it up via a short S-Video cable, if you still see the problem this will confirm that the problem is not your home-made cable.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>It is possible, almost probable, that the problem *is* your cable, and something is different between your laptop and your Myth box, for example your laptop probably has only one video signal, the S-Video, and not a differing VGA floating around.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>As you seem to realize, you have broken just about every rule about video cabling :-) But this doesn't necessarily mean you won't be able to get it to work.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>It could also be something like your laptop having a different grounding scheme, in fact it may well be more resistant to common-mode interference because the power supply is not referenced to your house ground, or the exact VGA rates of your laptop are just enough different as to render the problem invisible.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Changing the resolution of the VGA signal may well help your problem, the interference will still be there but the rate difference will be different and thus might well cause it to move through the picture fast enough to not be noticeable. Changing the rates of your VGA signal will have the same effect, though setting them to be the same as your TV may well cause an interfering bar to simply be static, unless you can "genlock" them to a fixed phase relationship, something beyond most PC systems.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>The README included with the nVidia driver explains how to set up clone mode, but having the same image on both screens is not the same as having the same video parameters.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>In short, your cabling arrangement is in all probability the source of your problems. Rules and standards exist for a reason. The type of interference you are having is very sensitive to the precise frequencies involved, if they are close enough to each other (or their harmonics or beat products are) then you will see visible artifacts, if they are far enough away from each other the products will move through the picture fast enough to not be a bother, but they are still there, and could be measured with the right gear. Differences on the order of fractions of a percent of the sync rates can make the difference, and these are well within the tolerances of modern video cards. Simply trying another "identical" card might make a difference.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>You could always use that cat-5 for what it was meant for - ethernet, and just put a MediaMVP at your set for about the same cost as a new video card :-)</DIV><DIV><BR class="khtml-block-placeholder"></DIV></BODY></HTML>