Eyefinity 6 with 3xU2711, one monitor limited to 1280x1024?

[rogergraham]

I have the 5870 Eyefinity 6 with three Dell U2711 native-DP monitors. All monitors are connected via MiniDP-to-DP adapters. I am running Windows 7 64bit, with 10.11 Catalyst drivers in CCC version 2010.1026.2246.39002, downloaded and installed fresh today.

The problem is that whilst the card will happily drive the 2nd and 3rd monitor at 2560x1440, the 1st monitor goes blank if I try to set anything higher than 1280x1024. This is true:

- whether I make the resolution changes in CCC or using the normal Windows Screen Resolution dialog box.

- whether I have the monitors at 75Hz (which apparently is the default rate) or 60Hz

- whether I try an Apple active MiniDP-DualLinkDVI cable instead of the MiniDP-DP cable

- whether I run one 5870 Eyefinity 6 or two

- whichever of the two Eyefinity cards is installed, i.e. I have tried both in case there was a card failure of some sort

- whether Crossfire is enabled on the second 5870 Eyefinity 6

As you can imagine, it's incredibly frustrating to have spent all that money with such a poor result.

The worst thing is, it worked for a while at 7680x1440 using the Apple adapter and drivers from ~6 months ago, and I have no idea why it suddenly stopped working.

Any ideas?

Cheers,
Roger

[rogergraham]

It seems no-one here can help; does anyone know anywhere else I can post this question?

[suiken_2mieu]

Is it just that monitor? Meaning have you tried just running that monitor that cant go above 1280x1024 at a higher res?

[rogergraham]

Thanks Suiken, not quite right but you inspired me to do some more rigourous tests... it turned out to be a faulty MiniDP-to-DP adapter. What a pain in the arse :-)

[suiken_2mieu]

Thanks Suiken, not quite right but you inspired me to do some more rigourous tests... it turned out to be a faulty MiniDP-to-DP adapter. What a pain in the arse :-)

Hell i know the feeling of faulty adapters. I've had to replace one of mine, and none of them work very well for me.