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View Full Version : How DVI and EDID works ?


Braqoon
09-05-07, 07:49 AM
Hi,

i have small problem with my monitor and nvidia, but i'm trying to understand the process.

I have Nvidia 6800GS (DVI-I & VGA) and brand new monitor Samsung SN941BW also with DVI (but DVI-D) and VGA.

when i connect monitor via DVI cable (supplied with the monitor) my card don't send signal via DVI output and therefore i can't see a thing.

when i connect monitor via vga it works but then i have problems with resolutions and need to do manual setup of res.

The strange thing happens when i switch to Linux and force nvidia to use DFP as a output. DVI suddenly starts working in graphic mode (but res. is crap ).

Now then i know that my monitor should send some EDID info to card that will allow nvidia to setup res. and all correctly. Nvidia claims (logs) that can find any EDID info.

Now then how it all works ? did monitor send some EDID on any output (vga or DVI) to graphic card and when PC is starting up, graphic card detect what kind of signal can send to monitor ? or EDID is not needed when Graphic card choosing with output to use ?

if some thinks about the DVI cable then bare in mind that i get working digital output but only when i force graphic card to use it, so i assume that cable is ok.

Thanks for all replays.

evilghost
09-05-07, 08:00 AM
EDID supplies timing information and frequency/resolution information to the video card. This is not synonymous with detecting a connected monitor. In your case, your TV does not supply any valid EDID information (based on what you said, if you did typo on 'Nvidia claims (logs) that can find any EDID info.').

The lack of EDID explains why the resolution isn't correct under Linux. You should be able to create a modeline and supply the correct frequency and resolution information.

Braqoon
09-05-07, 08:15 AM
yes, it's a typo. nvidia can't find any EDID info.

thanks for reply.