Hi

Win7 64bit
Radeon HD5770
2 1680*1050 monitors connected through VGA to the DVI ports using adapters
1 Projector connected through HDMI

I can get any configuration to work using two of these "monitors" but not 3. I can also set EyeFinity for any two of them but not all three at the same time.

AMDs documentation of this card says

ATI Eyefinity multi-display technology^4,5

• Three independent display controllers
  • Drive three displays simultaneously with independent resolutions, refresh rates, color controls, and video overlays
• Display grouping
  • Combine multiple displays to behave like a single large display

Which make and model of 5770 is this?

VGA to DVI ports using adapters? I don't recall seeing a vidcard with two vga ports and normally only one dvi port will provide analog (vga) signals.

Anyhow.. sounds like you need an ACTIVE adapter and you must use the display port for one monitor. Which brings us back to what exactly do you have for a 5770 and what cables/adapters are you using?

#1: Phenom II C2 955BE @ 3.6, Antec Kuhler 920, Gigabyte GA-MA790FX-DS5, Asus 5870/V2, ASUS Xonar D2X, 4 x 1gig OCZ2N1066SR2GK @800, Antec Truepower New 750, Arc Midi, Win8pro x64 upgrade
#2: Athlon 64 X2 4200+, AGP 1950pro, Audigy 2, Asus A8V-D, 2gig ram,  Enermax 465P, Antec900. Now on Win8pro cat 10.2

Clarification, it's not my computer but my dads but I'm quite sure it's this card:
http://www.motherboards.org/reviews/hardware/2096_2.html
XFX  HD 5770 850M 1GB DDR5 ...

It has 2 ports for HDMI and 2 ports for DVI. In both DVI ports there are DVI->VGA adapters with VGA cables to the monitors. BTW I just noticed that the montors would accept DVI as well. So there would be a difference in using VGA cables and adapters compated to using DVI directly?

I'll go look for some DVI cables...

I'm not 100% sure about HD5xxx but on 6xxx you can use up to two non-DP outputs at the same time.

This is due to framing constraints. Chip has only 2 framing electronics blocks, which actually freame the picture ( send individual pixels at the correct rate and sequence, generate sync signals etc etc).

Native DisplayPort doesn't need framing as it operates more like network card. Picture is send down the cable as a series of packets and it it monitors job to assemble them in picture, unpack audio etc etc.

So, for third monitor you either need something with DP input or ACTIVE adapter DisplayPort to something else ( VGA or DVI usually).

"ACTIVE" part is important since you can get simple ones ( that are nothing more than two connectors and a piece of wire), which are passive and when used, GPU will internally turn its DP output into compatibility DVI/HDMI mode and use one of the internal framing cirucits for framing.

You need ACTIVE adapter, which takes DP and frames it. I believe Sapphire has one or two cheap solutions they offer as an optional accessories.If you plan to use more than 1920x1200@60Hz at that output, take care to use dual instead of single link DVI adapter.

I have three monitor setup on my Sapphire HD6850 It's a 3x Syncmaster 20" 1600x1200 setup. Two monitors are connected through DVI and for the third I have DP to VGA adapter and it is connected through analog VGA input.

I must say this was not the best of choice, but I had to use it, since it was only available at the time. VGA signal is not 100% sharp and all details have small horizontal shadow. Not immediatelly visible, but annoying at long hours of precision work and close range.

It is not even discernible for other users ( games, movies etc), but I would still go for active DP-DVI. Once again, avoid passive ones.

Very interesting, so for 3 monitors one would have to use one DP port?

Thank you for the explanation. It makes sense, in this case however, we don't need all three monitors at a time, just an easy way to switch between double monitor and single monitor mirrored in the projector. Is this achievable through AMD CCC user presets? Is there any other possible way to easily switch between these two monitor configurations?

For this the User Presets work EXCELLENT! I've made hotkeys as well Thanks for your help! Now it will be very convenient switching between film mode and normal mode.

Happy New Year!

[SOLVED]

How do I mark this thread "solved"?

I can't tell you anything about Windows since I use strictly Linux ( Gentoo ), but I am sure Windows capabilites are at least on par with Linux, since most of effort nowadays goes into Win platform.

On Linux, three monitor setup works fine either with open source "radeon" or with AMD's closed source Catalyst. Catalyst was buggier but better with 3D, open source is better with 2D and surprisingly useable even with 3D.

In the past on Linux it was best to use AMD's tools like atiutils or ccc to tweak /etc/X11/xorg.conf and then tweak them by hand since such tools got confused quickly.

After using open-source drivers with manually tweaked config file for quite a while I decided to try Catalyst once again a few days ago and went for 12.11.beta11. I used ccc to setup xorg.conf for three monitors and it did its job fine - no need for manual tweaking.

As I said before, I can't tell you anything about WIn platform, though.

Here is a link to a pic of my three monitor Eyefinity setup:

For third monitor you need something like this:

http://www.sapphiretech.com/presentation/product/?cid=4&gid=1010&sgid=1011&pid=0&psn=000101&lid=1&leg=0

This one is cheap version with single-link DVI output. Dual-link ones were announced, but I couldn't find one cheap.

Other solution might be a DP splitter, but those are still expensive and of limited use at present. Matrox has one DP-3xDVI, but it costs €300 or so and I think I can dig out newer announcement somewhere for DP1.2 to 3x DVI, which sould be much more capable and cheaper, but was still vapourware at that instant.

Since new DP1.2 ( higher bandwidth, multistream capabilities) is out and actually used with new Trinity, it woould be nice to have cheap DP splitter for running multiple DP monitors from one DP source.