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Help, Asus HD7850 can only manage 2 monitors, not 3

Last response: in Graphics & Displays
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May 20, 2012 12:48:48 PM

I bought last week Asus HD7850DC22GD5 with expectation it can manage 3 monitors.
I have a PC with Asus P867MLE as motherboard, i3 and 4 GB ram. P8J67MLE has onboard video card.

My existing monitor is LG W2442PA, it has HDMI, DVI and VGA.
I bought Dell U2711 it also has HDMI, DVI and VGA and Dell U2412M, it only has DVI and VGA.

Asus HD7850 has 2 mini display ports, 1 HDMI and 1 DVI

I bought two apple mini display to DVI connectors.

Here is the setup
1) HD7850 DVI connect to Dell U2711, this is the only connection to get max resolution 2560 x 1440.
2) HD7850 Mini Display connect to LG W2442PA
3) HD7850 Mini Display connect to Dell U2412

Only 1) and 2) are working, 3) went to save mode. When I disconnect 2), the third monitor 3) automatically go to active mode.
I tried HDMI to connect 2), the same behaviour as above, when HDMI connected to 2), then 3) automatically go to save mode.

So at all of these experiments, I can only connect two monitors to HD7850.

I cannot install another HD7850 because the mother board only has 1 slot. It seems also the VGA/DVI integrated with the mother board is also inactive.

I do not need eyefinity. This build is for software development only,
- left monitor LG for reference, ebooks
- middle monitor, U2711 for programming/coding using IDE
- right monitor, for testing the program


Any thoughts or advices? Do I need to buy a more advanced graphic card? or can I chain the monitors?

Thank you.


Asus HD7850
http://www.asus.com/Graphics_Cards/AMD_Series/HD7850DC2...

Asus P8H67 MLE
http://www.asus.com/Motherboards/Intel_Socket_1155/P8H6...
a b C Monitor
May 20, 2012 1:21:39 PM

Again, I have to stress the importance of using an active adapter to enable the third screen in most AMD card.

From Apple:

9. What is the difference between an active adapter and a passive adapter?

An active adapter can convert a signal from one connector to another. The Apple Mini DisplayPort to DVI and Apple Mini DisplayPort to VGA adapters are active adapters. A passive adapter acts as a pass-through from one connector type to another and does not convert a signal. The Apple Mini DisplayPort to Dual-Link DVI adapter is an example of a passive adapter.

Did you get the active adapter?
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May 20, 2012 1:41:31 PM

Yes, I got two mini to DVI adapters, from Apple.

Both of them are working fine, although the resolution from miniports of HD7850 are only 1920x1200.
The max resolution from the DVI port of HD7850 is 2560 x 1440. The max resolution of the monitor Dell U2711 is 2560 x 1600, a little bit higher than the graphic card.

I tested, both of miniports are working, when connected to two monitors. Listed below is one of scenarios that I have tested.
step 1: miniport 1 connected to LG W2442PA, it works fine
step 2: miniport 2 connected to Dell U2412M, it works fine
step 3: DVI, connected to Dell U2711, results: U2412M stop working, going to save mode. U2711 and LG W2442PA are both working.

So only two monitors are working and one is doing save mode. I tried different combinations, all works fine for two monitors, but not three.


Mini to DVI (active)
http://store.apple.com/au/product/MB570Z/A (edited, now the link is correct)
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Related resources
a b C Monitor
May 20, 2012 1:56:20 PM

The one you link is not even a mini displayport to DVI adapter.
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May 20, 2012 2:00:39 PM

Quote:

The one you link is not even a mini displayport to DVI adapter.


Ooopss, sorry, I fixed the link.
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May 22, 2012 1:24:10 PM

Thanks Pyree.

What I have tried so far....and does not work
- apple minidisplay port to DVI, apple staff told me, it can only run two monitors, so it does not work for three monitors. I returned one of the adapter, still have another one.
- bought a minidisplay port to DVI from wickedwired.com.au. It has dual link, mini display port and DVI. It does not work, I will return it to the shop tomorrow.

From reading the whirpool forum...these adapters have been validated for AMD

My AMD HD7850 Asus has
- 2 mini display port
- 1 DVI
- 1 HDMI

From the eyefinity setup in this forum
I will need to get
- 1 DVI cable (come with the monitor)
- 1 HDMI to DVI adapter (need to buy this one)
- 1 Minidisplay port to DVI, active
If i get the single link, the resolution only 1920 x 1200
If I get the dual link, the resolution 2560 x 1600


I will try to get these adapter, will post an update.

mini display port to dvi (dual link)
http://jayveetechnologies.com.au/av/accell/accell-displ...

mini display port to dvi (single link)
http://jayveetechnologies.com.au/av/accell/accell-displ...
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a b C Monitor
May 23, 2012 2:00:58 AM

Try connect LG with DVI to mini displayport active adapter, Dell U2711 with HDMI and Dell 2412m with DVI.

One of the display must be connect to the DP.

Use staticice.com.au to find the cheapest verified active adapter.
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May 27, 2012 2:22:37 PM

Thanks Pyree!
It is working now, partly :) . The setup is

- LG W2442, on optimal resolution 1080x1920 portrait, connected to mini display port (mDP) using Apple mDP (GPU) to DVI (monitor), left side
- Dell U2711, on optimal resolution 2560 x 1440 landscape, connected to DVI (GPU) to DVI (monitor)
- Dell U2412M, on optimal resolution 1200 x 1920 portrait, connected to mDP using Mini DisplayPort 1.1a with HDCP1.3 to DVI-D Dual-Link Active Adapter similar to this one, http://www.accellcables.com/products/DisplayPort/DP/mdp... . However this cable is a generic no branded cable, it is branded by the computer shop as wickedwired.com.au. Max output is 1920 x 1200@60Hz.

It only works, if the active mDP-DVI adapter is disconnected from GPU, when the computer is started/powered on.
After two monitors on and the login screen is displayed (not before the login screen is displayed), the active mDP-DVI adapter is connected, then the third monitor works.

I will need to redo this annoying task when I restart my computer. Two monitors are on, the third monitor is asleep. The two monitors went black, the third monitor is still asleep. I disconected the active mDP-DVI from GPU for about 5 seconds. One second after mDP-DVI disconected, the login screen appears, two monitors active again, not black. After I connected the active mDP-DVI, the third monitor is active. All good untill the next restart.


May be the Dell monitors are the problem, or the cable, not sure yet. I will buy the cable/adapter from Accell to ensure the problem is not the cable/adapter.
http://en.community.dell.com/support-forums/peripherals...
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a b C Monitor
June 27, 2012 8:10:36 AM

Could you please post pics of the setup here, we'd love to see them..... :) 
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