640x400 not working over DVI??? (1 Viewer)

[dajdroge]

Hello!

I have ecs amd690gm-m2 motherboard. It has vga and dvi-d outputs. While using vga to connect to DVI-I on my Benq W100 projector, 640x400 resolution works perfect. So, recently I bought DVI-D cable (dual link for some reason), and connected my htpc via DVI to projector. And now, I can not get it to work with 640x400. 640x480 or higher works. On-board graphics is ati x1250, so I think it could be graphics card issue? Did anyone have similar problem? It sounds funny, but since projector supports 640x400 using DVI-I (meaning, I can connect VGA via DVI adapter, or DVI-D), it really could be DVI-D on x1250 not supporting 640x400???

 

[and-81]

It could be that 640x400 isn't supported on DVI-D (or maybe just with your card).

I can't find anywhere that says DVI-D supports 640x400, but I can't find anywhere that explicitly says it doesn't either.

All the information I've found says that DVI-D supports 640x480 and above.

I think you are stuck with analog video at that resolution (VGA 15 pin D-SUB or DVI-I/A).

As a last ditch effort you could try different refresh rates (try 85hz first) to see if it comes good, or maybe even try PowerStrip to set up a custom timing...

Good luck with it,

 

[dajdroge]

Dvi-d works at 640x400, at least it works with x1950 Friend has x1950, and lcd connected with dvi-d, and he managed to get 640x400.

 

[and-81]

DVI-D devices have to support 640x480, it's part of the spec, but I don't think they have to support 640x400. So it could be either the Video Card or the Projector.

Also some devices don't support the same resolutions on VGA DSub as they do on DVI-D so it could be that is the problem.

Here's some more info on DVI ...

http://www.playtool.com/pages/dvicompat/dvi.html
http://www.playtool.com/pages/dvitrouble/dvitrouble.html

I did some googling and found a few ATI cards that don't support that resolution. Though I didn't find yours exactly.

Cheers,

 

[dajdroge]

DVI-D devices have to support 640x480, it's part of the spec, but I don't think they have to support 640x400. So it could be either the Video Card or the Projector.

Also some devices don't support the same resolutions on VGA DSub as they do on DVI-D so it could be that is the problem.

Here's some more info on DVI ...

http://www.playtool.com/pages/dvicompat/dvi.html
http://www.playtool.com/pages/dvitrouble/dvitrouble.html

I did some googling and found a few ATI cards that don't support that resolution. Though I didn't find yours exactly.

Cheers,

I managed to solve the issue, thanks to powerstrip and advanced timings. In fact, the way I see it, DVI works from 25Mhz, so 640x400@60Hz was on the borderline, being 24.96 to 25.17Mhz. Since playing with Mhz didnt work, I simply set it to work at 640x400@75Hz being around 31Mhz and that did it. Thanks and-81 for help

 

[and-81]

cool

 

[automated]

640x400 is a bit low, especially considering the native res is 854x480. I would try 720p (1280x720).