just follow the instructions for using three displays per 5770. you will of course block another PCI slot and only have 4x (mabe 8x) on the 2nd 5770.
Apple Mini DisplayPort adapters: Frequently asked questions (FAQ)
Guide to Apple graphic display adapters needed
Atlona (Dual Link) DVI to Mini DisplayPort Converter for Apple 27-inch LED and 27-inch iMac
we can connect up to 6 monitors with mini-display port ... it does not mention Display Port models, that can be connected via a Display / Mini Display port adapter.
DisplayPort is electrically the same as Mini DisplayPort. The adapter is simply a re-assignment of the pins to the different connectors. Some users find this adaptation is better performed with an adapter-cable, rather than a discrete adapter. Rules that apply to Mini DisplayPort stand exactly the same as (full size) DisplayPort.
connect 2 monitors with DVI to Mini DP adapters AND 2/3 monitors with Display to Mini DP adapters at the same time ?
These appear to be limited to 2 Single-Link DVI adapters unless you use USB-powered ACTIVE adapters. This setup is complicated, and that is not "The Apple way". it may suddenly require ALL adapters be ACTIVE adapters.
VGA to Mini DP adapters : does that mean that I can use 5/6 monitors at the same time that way ?
No. These will also be limited to easy use with the two display adapters. In today's digital display age, VGA is not a solution to anything. It is grudgingly provided to run your old projector.
All VGA Adapters are ACTIVE -- they contain a chip that generates the Analog signal from the DisplayPort signal provided, and the VGA signal degenerates further in the process, and has limited resolution. There are no VGA Adapters which have the extra USB input, so that alone may limit you to the two specified.
For completeness, keep in mind that a 4K display can use up to 14G bits/second (variable depending on how much is changing on screen) for a moving picture, so there may not be as much as expected left over on that 20G bits/sec ThunderBolt channel (2 ports/channel) to run your Drives.
Thank's for your complete answer.
If I understand you correctly :
1 - 5/6 monitors with DP to Mini DP should be no problem.
2 - Mixing 2 single link DVI / Mini DP adapters and DP to Mini DP adapters might result in problems, but though it is not the "Apple" way, it may work.
3 - Noted : forget about VGA !
4 - I do not intend to use 4K displays for now so I am not concerned by them for now.
2. additional clarification:
I am sure two adapters to Single-Link DVI will work fine.
I expect you can mix in additional [Mini] DisplayPort cables for up to six displays.
What we do not yet know for sure is 'pressing on beyond two DVI displays'. It is not specifically precluded by that article, but it could get really complicated, with lots of expensive adapters that need additional (USB or equivalent) power.
I have now moved to my MacPro 2013 and I have those 2 questions :
I followed your advice and have now 3 DP monitors linked via DP / MiniDP adatpors, as well as two DVI linked by the Apple DVI / MiniDP adaptors and all of them are working fine ( at least I have no problems while using them for my work )
However, when checking I noted that all my monitors are powered by only one graphic card ( the one in Slot 2 ) while the one sitting in Slot 1 does nothing ...
Is this normal or am I doing something wrong ?
Also, the boot time is very long ( close to one minute ) with multipe messages from the Windows Server so I wonder wether those 2 issues are linked or not ?