Problem with Dual Displays, Powermac11,2 2x2.0, 6600LE

[phyrexia]

Hello All.

I have a Powermac11,2 with the 6600LE video card, 10.5.8, recent software updates. I have been using two displays for some time now with no problems whatsoever.

I recently replaced one of the monitors with a higher resolution unit and now, if I boot my machine up with both monitors connected, this happens:

I had an Acer 21.5" 1080P monitor and Hanns-G monitor which ran at 1440x900, IIRC. I replaced the Hanns-G with a Samsung 2333T, and I'm now using the 2333T as the main display. So now I have two 1920x1080 displays.

Turning off the secondary monitor does not fix the problem. Unplugging it doesn't either. However, if I boot the machine with the secondary DVI cable unplugged and plug it in once the system is up and running, I don't have the problem. Likewise, once the system is up and running as pictured above, I can unplug a DVI cable and plug it back in, and the system appears to reinitialize the display and everything is back to normal.

Thanks in advance for your thoughts.

 

[macdatadrive]

I think perhaps you may have a faulty cable. See, because you aren't using an Apple display I also could say it could be problem with monitor. I believe maybe your monitor cannot handle Leopard. Try resetting the video card and if all else fails, go to System Settings and check the displays.

Hope that helps a bit.

 

[AdrianK]

I believe maybe your monitor cannot handle Leopard.

That doesn't make any sense, monitors will show whatever graphics are rendered out by the GPU unless they don't conform to the monitors specs in some way (incompatible resolution, refreshrate etc).

 

[chrismacguy]

That doesn't make any sense, monitors will show whatever graphics are rendered out by the GPU unless they don't conform to the monitors specs in some way (incompatible resolution, refreshrate etc).

And even then, its not the monitor thats at fault. My best guess would be the graphics card is slightly confused about what to put on each screen - Id try and replace the GFX Card, since it appears both monitors are receiving pieces of each others signals, which I don't think could be a cable issue unless your using a splitter to get 2 monitors off a single display out.

OP: Also, does it occur if you run the monitors below their stated resolution (ie run one of them at 1600*900/similar)

 

[phyrexia]

Setting the secondary display to a lower resolution fixes the problem.

Interesting...

 

[chrismacguy]

Setting the secondary display to a lower resolution fixes the problem.

Interesting...

Sounds to me like your graphics card is having issues pushing pixels to 2 displays at 1920*1080 - It might be easiest to upgrade the graphics card to a more modern card that can handle that resolution correctly.

 

[phyrexia]

The whole setup works fine together, at 2x1080, just not at boot. It has run for 10 or 12 days straight with no issues once I pull a DVI cable after it boots. I only paid $100 for this machine. So I hesitate to replace a video card with an obsolete $350 Mac video card.

Is this something that might be solved by an NVRAM reset?

 

[chrismacguy]

The whole setup works fine together, at 2x1080, just not at boot. It has run for 10 or 12 days straight with no issues once I pull a DVI cable after it boots. I only paid $100 for this machine. So I hesitate to replace a video card with an obsolete $350 Mac video card.

Is this something that might be solved by an NVRAM reset?

It wouldn't hurt to try it Id've thought. It might fix it (It could even be a dodgy cable or something as odd as that, but NVRAM is a good place to start). - Nice machine for $100!