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Connecting three displays to a 5870 - DVI non-functional

F

FluJunkie

macrumors 6502a
Original poster
Jul 17, 2007
618
1
I've got three displays, essentially the results of a slowly accumulated collection rather than setting out to get three displays, but I figured I'd try a triple monitor setup before committing to buying nicer screens. They are:

1. A 23" Dell Ultrasharp, connected via a miniDP -> DP cable
2. A 26" Song Bravia HD TV from the pre-1080p era, connected via a miniDP -> HDMI cable
3. A ~20" ancient IBM branded LCD, connected via the 5870's DVI port.

1 & 3 were serving loyally and well while 2 was acting as a TV. We got a new TV, and thus the Bravia was just sitting about, so I tried connecting it.

1 & 2 also work fine, when I disconnected the IBM monitor waiting for a longer power cable. But when I connect all three, the DVI connected display remains blank, and doesn't activate. If I unplug one of the miniDP connected displays, it's detected and comes on instantly.

Googling more, this appears to be a known issue, using a DVI and an HDMI connection simultaneously. Delightful :\

Any ideas for a work around? The available connections for the TV, which appears to be the problem, are VGA and HDMI.
 
Last edited:
Point of failure is converting Mini DP to HDMI.

There is no combination in which you can connect all three displays when one Mini Display Port is converted to HDMI.

If you can use DVI to your TV and audio through optical / analog out from your Mac.

DVI combinations:

1. Mini DP to DP
2. Mini DP to DP
3. DVI to DVI

*************

1. Mini DP to DP
2. Mini DP to Active DVI adater (1920x1200 max)
3. DVI to DVI

************

1. Mini DP to DP
2. Mini DP to DL DVI Adapter (2560x1600)
3. DVI to DVI
 
FluJunkie said:
Would DVI to VGA added on to the end of either 2 or 3 work?
Click to expand...

It would work 100% at the end of the 3, DVI to VGA.

Avoid any conversion of Mini DisplayPort for tripple monitor setup. If you must, convert it with active DVI adapter.
 
bax2003 said:
It would work 100% at the end of the 3, DVI to VGA.

Avoid any conversion of Mini DisplayPort for tripple monitor setup. If you must, convert it with active DVI adapter.
Click to expand...

I don't believe this is correct.

I think he would need active VGA conversion. VGA and DVI are considered "legacy" ports. There are only clock generators for 2 of them on the card, any more and you need "active" adapter.
 
Best thing for him is to use first display on display port, second with active DVI adapter (max 30$) and TV just with DVI to VGA adapter.
 
bax2003 said:
Best thing for him is to use first display on display port, second with active DVI adapter (max 30$) and TV just with DVI to VGA adapter.
Click to expand...

Any chance you could link to an appropriate active DVI adapter? There seem to be an abundance of Mini-DP to DVI adaptors, and I'm not sure which ones are suited.
 
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