6

I have an interesting, yet very frustrating problem. I have two computers, both running win7 32 bit, and both with ATI Firepro V4800 graphics cards. Both are using the DVI port and two DP to DVI adapters to connect 3 monitors.

One of them is able to display three desktops, while the other fails at enabling the third, displaying "cannot save changes" in display properties while requiring that one monitor must be disabled when making the change in CCC.

I've verified that both computers have the same driver version and that both are using the same DP-DVI adapters.

This articles suggests a few things to try, but none of its suggestions seem to work either.

I'm kind of at my wits end, hence my posting here. If this is not an appropriate question for SU, I apologize.

I admit that I am not very familiar with the differences between dual link and single link DVI, and that is something I have not verified is standardized between the two computers. Is that a possible reason one is working and the other isn't? How do I check if the DVI cable is a single link, or dual link?

fixer1234
  • 28,064
Jared275
  • 79

3 Answers3

3

Are all three monitors exactly the same on both computers? If not, you may be hitting a resolution limit.

The V4800 is an Evergreen-era GPU (actually one iteration later) so I'm a little surprised that it doesn't support up to three 1920x1080 displays...

I admit that I am not very familiar with the differences between dual link and single link DVI, and that is something I have not verified is standardized between the two computers. Is that a possible reason one is working and the other isn't? How do I check if the DVI cable is a single link, or dual link?

Single link DVI has "missing square pins" or "missing holes" (depending on whether you're looking at male or female connector).

Dual link DVI has square pins all the way across.

The difference:

various DVI connectors pinouts

Single Link has a lower maximum resolution (or lower refresh rate if higher resolution) because it can transmit less data with less pins. Dual Link can transmit the highest maximum resolution / refresh rate. Cable lengths also can affect resolution.

For a full description, see Wikipedia.

allquixotic
  • 34,882
2

Uninstalling, and completely removing all of the driver files with the Driver Fusion utility recommended here, and then reinstalling driver 8.773.1.1000 seemed to do the trick.

I suspect that installing the newest driver would have worked as well, but I knew that the older driver worked on the other computer, and I didn't want to risk having to do the process again.

Thanks to Hennes for recommending this approach, and allquixotic for the info on DVI,

Jared275
  • 79
1

I had been using two passive DisplayPort-to-DVI adapters and one plain DVI cable fine when I was running three monitors; two were the same size, and one was a larger size. I was able to fix this problem by switching one of the adapters to be an active DisplayPort-to-DVI adapater.

Now the V4800 runs three monitors with different resolutions successfully (1680x1050, 1920x1200, and 1280x1024).

Jon Onstott
  • 248