DVI issues

nicthemighty · 22 Jul 2010

I received my new custom PC yesterday, delivered without a graphics card or OS. It has been tested with an ati graphics card, and installed/tested windows 7, then wiped.

I installed my graphics card (8600GTS) plugged in my benq g2410hd DVI monitor, and could not get any output on the screen - no POST or anything. I plugged in an older LG DVI monitor, and that worked fine, so I reset the bios to default settings, and installed windows 7. I then ran all the updates, new graphics drivers etc.

I then plugged in my Benq monitor as a second monitor, tried to detect it, and windows blue screened (nvdlmkm.sys I think). I uninstalled/reinstalled the graphics drivers a few times, and eventually I could plug in and detect the Benq manually using the windows screen resolution settings window. However, windows detected it as a "non-pnp" monitor, but allowed all resolutions (above natvie too). If I then loaded the nvidia control panel, it disabled the Benq, and claimed it couldn't find a second monitor (just my LG as primary).

I turn the pc on with the Benq in the second monitor, I get all the video on the LG, then I can manually detect the Benq (with the "non-pnp" issue) - but this time it restricts to 1280x768 (but the Benq osd says it's at native 1920x1080).

I have tested the Benq on a different machine, and dvi works fine. I have plugged a different monitor into my pc, and it is detected without any issues. Also, I was running the Benq & LG dual screen on my old pc, with the 8600GTS, without any issues.

Strangely, if I plug the Benq using a vga->dvi adaptor, I get a vga signal on the Benq without any problems - post screens, boot screens, and windows. Windows then detects it as a Benq without any problems, and I can dual screen without any issues at all.

So all I can assume is that something to do with Benq -> 8600GTS -> new PC that is stopping the Benq being detected correctly by the graphics card...

Does anyone know what might cause this, or experienced it themselves? Google appears to have very little information about it! I assume it's not OS related as the issue happens on boot/post.

Mellon Head · 22 Jul 2010

There are two types of DVI connection. DVI-I and DVI-D. DVI-I is an integrated digital and analog signal, where DVI-D is digital only.

It might be a cabling issue, or the DVI output on the graphics card may not be the type of signal that the Benq requires. The fact that it works on another card, and it works with a VGA adapter leads me to think that it uses a DVI-I input, and your card might be putting out DVI-D which may not allow the Benq to give Windows the EDID information (the monitor's modes and parameter info) it needs to properly detect it. See if you can find a DVI-I cable and connect it. That may solve the issue.

Here's a link to some DVI info:

http://en.wikipedia.org/wiki/Digital_Visual_Interface

I hope that helps a little bit. Post back if you have more questions.

nicthemighty · 23 Jul 2010

I checked the monitor spec, and it's dvi-d input, and also d-sub. I'm not sure what type dvi cables I have - but would that make a difference with dvi-d?

Does this affect it before boot or only in windows? Because I can't even see bios/post screens over dvi.

Thanks for the quick reply though!

ionbasa · 23 Jul 2010

the cable shouldn't matter I belive, but durring boot up / post expect it to only display on the primary monitor. thats my case and then 2nd monitor comes online automaticly during logon, but then again my samsung 36" tv is UPnp compatible.

nicthemighty · 23 Jul 2010

Hi all. The monitor won't post if I put it in the primary port. I checked for compatibility, and microsoft claim the monitor is supported on win 7 without needing any drivers.

The monitor has worked on this graphics card in the old pc - it only won't work in the new pc. So the only thing I've changed is the mobo/cpu/ram.

I've flashed mobo to newest bios and this didn't fix it. Is it possible there could be an incompatibility that would cause the one monitor not to work?

Also, the Benq is hdcp, whereas the LG isn't - though presumably hdcp doesn't affect bios/post screens?

Mellon Head · 23 Jul 2010

I'm not really an Nvidia expert, I'm more into ATI, but it sounds like something isn't working right between Windows 7 -> the card -> the monitor. I had a look at some of the specs for the mobo, video card and monitor. I don't think there's any reason it shouldn't work...

nicthemighty · 23 Jul 2010

I'm assuming it's not a win 7 issue as i couldn't get the bios or post screens even before installing an os...

I was planning to get a new graphics card some time soon - think it's worth just ignoring this card and moving on?

Thanks again for the help!

nicthemighty · 23 Jul 2010

Oh and other specs - 4gb ddr3, i5-760, asus p7p55-m.

Mellon Head · 23 Jul 2010

If you have a buddy that has a spare card, or one he can lend for a test, you might give that a try. There are better cards around, for sure, but I guess it depends on your financial situation. There isn't much sense throwing out a good card if it isn't broken. Do a little more testing before you junk it.