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How many 2560x1440 monitors can a single AMD 7000 support? e.g. HD 7950? AMD says up to 6 monitors but no word about the max number of monitors at this resolution.

edit: My bad, Shinrai is correct. The question is: How many 2560x1440 monitors can an AMD 7000 drive from a single DP port?

From those documents:

1) http://www.vesa.org/wp-content/uploads/2010/12/DisplayPort-DevCon-Presentation-DP-1.2-Dec-2010-rev-2b.pdf (page 11)

2) http://www.vesa.org/wp-content/uploads/2011/01/ICCE-Presentation-on-VESA-DisplayPort.pdf (page 19)

We have this graph: DP Graph

and it's clear that DP 1.2 can ONLY support 4 1920x1080, 2 2560x1600 monitors and 1 4096x2160 monitor @60Hz and 24 bits per pixel. Can someone please explain why? How they calculated this?

In my understanding 2560x1600x60x24 = 5898240000 bps = 5.898 Gbps Now, 5.898*2 = 11.796 But on the graph is at 13-14 Gbps. What I am missing?

Also, DP supports up to 17.28 Gbps if we take this documentation as correct. On the other hand AMD says their cards support 21.6 Gbps. DP 1.2 max bandwidth is 17.28 Gbps or 21.6 Gbps?

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This depends more than anything on the exact SKU and the ports it has. In theory, the chipset will support six displays all running at 2560x1600 or better (a card which almost certainly would be six mini-DisplayPorts, and there are a few floating around out there), but just because it's capable doesn't necessarily mean any six-port card will automatically be capable of it.

EDIT: In response to your edit - do you have DP1.2 capable monitors? I'm not aware of anything on the market that supports daisy-chaining aside from the current Apple Thunderbolt displays...and you can run two of those daisy-chained to a single port. I believe this limitation is in the DisplayPort 1.2 spec, so theoretically anything that supports it should have exactly the same limitation - two monitors of that resolution per channel. (Basically, this is exactly what your chart says). The card might be able to push more but it's outside spec, so don't assume that it will.

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Does Apple Thunderbolt Display fully support Daisy Chaining? How is this possible without DP 1.2? Dell u2713H and Dell U2913WM support DP 1.2. Both released recently. Yes, the graph shows you can DP 1.2 can support 2 2560x1600 monitors. The question is: how many 2560x1440 monitors can support? 2 or 3? –  ShadowHero Feb 1 '13 at 20:54
    
My impression is that 1440 and 1600 vertical resolution are interchangeable in this scenario - that is to say, you'll still get two. And yes, Thunderbolt Display is daisy-chainable (that's one of their big marketing points) - Thunderbolt is a superset of DP1.2. –  Shinrai Feb 1 '13 at 21:14
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