The 5770 is capable of supporting three displays if you do everything right. You can Extend the Desktop and/or Mirror the displays in any combination.
When you Mirror Displays, they WILL be set to EXACTLY the same resolution, no negotiation on that issue.
The issue with three displays is that the signals provided by Mini DisplayPort through a converter are correct polarity and timing, but not a high enough Voltage for reliable operation unless you use an adapter labeled as ACTIVE to boost up the signal level.
Single-Link DVI adapters are good for up through 1920 wide. Third-party ACTIVE adapters cost about US$35.
Above 1920 wide, you need to use Dual-Link DVI ACTIVE adapters, and these have doubled data lines which require even more boost power. These often include a USB lead to pick up power from a USB port. Dual-Link DVI ACTIVE adapters, like the Apple adapter, cost about US$100.
When you have three displays, you can mirror a display by dragging and dropping its screen-area on top of the screen you want it to replicate. The resolutions of both displays will be reset to the highest they can BOTH implement.
HI Grant, thanks for the answer.
I suppose using a Flashed firmware card will throw some variables into the situation ? for example, my card has 2 dual link DVI ports,1 HDMI and 1 Displayport.
I couldn't get the Displayport output to work with my HPZR2740w monitor for some reason. I'm guessing it's the firmware?
I did manage to mirror 2 screens and have 1 separate screen before, but that was by installing a 7300 GT card along side my 5770 and using one of it's DVI outputs as a 3rd screen, but unfortunately the performance of the duplicated screen was too slow for my needs (Pro Tools).
I guess what I'm trying to find out is if I buy an official Apple 5770 whether it will also suffer from low performance when duplicating in the way you mentioned above?
Mirrored Screens on the SAME card are really fast.
Screens wider than 1920 bits horizontal (and that HP at 2560 wide is a lot wider) require Dual-Link DVI everything, including (Mini) DisplayPort --> Dual-Link DVI ACTIVE adapter, about US$100. If it would work without this expensive thing, nobody would use it!
The main impact of Flashed cards is that the boot-up screens don't work. But sometimes certain (unexpected) ports don't work either.
Ok, that must be the problem then, the flashed card...
Because when I connect both Dual link DVI ports to the 27" HP screens, then add the HDMI to another screen, I only get 2 displays working at the same time, never 3, even at lower (compatible) resolutions.
When I unplug 1 of the HP's it then detects the monitor on the HDMI port and vice versa.
Do you think using the following arrangement would make any difference?
- Displayport -> Active Displayport / Dual link DVI Adapter to HP monitor 1
- DVI port1 -> second HP monitor
- DVI port 2 -> Normal lower res screen
And then runninf HP monitor 2 and the lower res screen both at 1080?
(Mini) DisplayPort conversion to DVI (or HDMI) may require an ACTIVE adapter. Converting it to Dual-Link DVI (or HDMI) requres a very expensive Dual-Link DVI ACTIVE adapter.
If you have two direct Dual-Link DVI ports I would cable them directly to your hi-res displays.
Then I would get an ACTIVE Single-Link adapter to DVI, and if needed, a DVI --> HDMI cable
Ok, but if I use both the DVI's for the hi-res displays then that leaves only the HDMI or Displayport to attach to the 1080HD screen to, but as I mentioned, when I have all 3 displays connected, only 2 work. DVI + HDMI or just 2 DVI. I never got all 3 working, hence my wondering if it's due to it being a Flashed card, not official Apple.
Do you think it would work if I connected 1 DVI to hi-res display, 1 Displayport to hi-res display and the 2nd DVI to the 1080 Display?
I read that Displayport cables need to be version 1,2 compatible in order to carry 2560 x 1440 resolutions, perhaps the Displayport cable that came with the displays is a version below 1.2? and that's why it never worked?
Here is a pic of the back of the card for clarity:
Just a quick update:
I ordered this:
It says it's ATI compatible, and I also found a post here, where someone successfully used one with their mac (running boot camp at least).
It's defintely a chaper option than trying to convert the Displayport into DVI for the hi-res monitors.
I'll post here how it goes.
I never got all 3 working, hence my wondering if it's due to it being a Flashed card, not official Apple.
according to AMD/ATI:
Connecting multiple monitors for AMD Eyefinity technology couldn’t be simpler. There are four easy rules to remember:
- The first two monitors can connect to the graphics card with any display output on your product: HDMI, VGA, DVI or DisplayPort.
- The third (or greater) display must be connected to the graphics card via DisplayPort.
- If your monitor does not have a DisplayPort connection, you will need an inexpensive active DisplayPort adapter for it. DVI to DP adapters can be had for less than $30 USD.2
- Every family of GPUs supports a different maximum number of displays.
ok, so a quick update:
I got hold of the Saffire DP to Single Link DVI adapter and it doesn't work either
The screen is detected by OSX, but only a blank screen shows up and the monitor goes into sleep mode. I tried this with several different DVI, single and dual link cables and HDMI... nothing...
The strange thing is, someone else in another forums said they had success with this adapter... I'm beginning to think it's really because it's a Firmware flahsed card..
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