Marcus L. Rowland (ffutures) wrote,
Marcus L. Rowland

DVI-D and DVI-I output to VGA monitor?

Another computer thing, not at all urgent but all suggestions very gratefully received...

My desktop PC has a graphics card with DVI-D and VGA ports. My big widescreen monitor has a VGA port only, and works very nicely on the card; the snag is that I would also like to run a cable to the TV for those occasional moments when it would be useful. Needless to say, the TV is also VGA only, and lower res than the monitor. I REALLY don't want to mess with splitter cables or boxes since they usually screw up the graphics on both screens to some extent, and because this may only see use once or twice a year. Another complication is that the shortest cable run for this is about 20 ft

My idea was to use a DVI-D to VGA adapter and VGA over CAT6 ethernet cable adapter.

VGA over CAT6 worked brilliantly - I can connect e.g. the iBook to one end and the TV to the other and get a perfect picture, got a 15 metre VGA lead for about a tenner. You use CAT6 to get a better signal, CAT5 allegedly deteriorates past 10 metres.

Unfortunately a DVI-D to VGA adapter does not seem to work at all. Not to my monitor, not to the TV, etc., regardless of the cable used. The computer behaves as though there is no monitor present at all.

Before anyone asks, the DVI-D output IS working - if I plug in a monitor with a DVI port and cable it works fine, but that monitor is crappy in other respects so I keep it as an emergency backup. When I try it with the adapter and the VGA port of a monitor it doesn't know it's there.

I'd assume that the adapter or card is borked in some way, but the little netbook I bought recently has a DVI-I dual output; to test it I borrowed a DVI-I to VGA cable from work, we ended up with several spare when we bought some projectors years ago, but that doesn't want to work either - again, it's fine if I connect the netbook directly to the DVI port of the monitor with a DVI - DVI cable.

So... if my experience is typical, DVI output to VGA doesn't appear to work at all, except for things like Ibook adapters which have this sussed in some way. I can only assume that the cheap adapters are intended for plugging a VGA source into a DVI socket, and you need something better to do it the other way. This begs the question of what the netbook guys thought they were doing putting that port on it rather than VGA, but it's far from the only bit of weird design in that netbook.

Anyone got any suggestions?
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