Mid 2010 MP ATI Radeon HD 5770 card mini display port problem

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Level 1

8 points

Mid 2010 MP ATI Radeon HD 5770 card mini display port problem

I have Mid 2010 Mac Pro with ATI Radeon HD 5770 card running OS X 10.9.5. It's been a while since I found that the mini display port(s) no longer display any signal on my 2nd monitor. It worked fine with 2-monitor setting before. I use an external mini display to DVI adapter.

It first happened when i upgrade my Apple 20 inch Cinema Display monitors to 2 Dell 27 inch monitors. Only the one hook on the DVI port will work, so i thought it might be the resolution limit of the graphic card. Now i go back to the Apple monitors and the Mini Display Port no longer working. Someone suggest to a similar post said it might be the bad adapter, so i just ordered a new one to try. Other than the adapter, would it be the bad Mini Display Ports? I tried both of them.

Please help.

Mac Pro (Mid 2010), OS X Mavericks (10.9.5)

Posted on Feb 17, 2016 11:48 AM

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Answer 1

Feb 17, 2016 12:20 PM in response to tljou

This is not a resolution-limit problem. This card can run three 30-in Cinema Displays at 2560 by 1600 each.

Modern display cards produce signals at the new lower DisplayPort signal levels, which are lower than "legacy" signal levels.

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To debug the use of adapters from Mini DisplayPort to anything else (except full size DisplayPort, which is not a conversion, just a re-wire) Boot up your Mac, then connect ONE display at a time. This removes a know issue with the card running out of power to convert Mini DisplayPort signals to "legacy" display signal levels (which are much higher).

If you have NO problem interfacing one at a time, then you may only need ACTIVE adapters (which contain signal-level boosters) to some of the legacy displays. This can allow you to run multiple legacy displays.

Users find that two legacy displays with ordinary adapters usually works, three never does, and requires at least one ACTIVE adapter.

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Answer 2

tljou Author

Level 1

8 points

Feb 17, 2016 2:28 PM in response to Grant Bennet-Alder

Thank you for your help. Can you explain what's ACTIVE adapter? Does the one i have or similar one work? There are 2 power suckets on the mother board for the graphic card. Does it matter which one i plug in?

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Answer 3

tljou Author

Level 1

8 points

Feb 17, 2016 2:42 PM in response to Grant Bennet-Alder

I tried to reboot and connect the monitor one by one but the Mini Display ports won't work at all. i just ordered new adapter to see if it's the bad adapter.

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Answer 4

Feb 17, 2016 5:00 PM in response to tljou

ACTIVE adapters boost the signal levels that start out at Mini DisplayPort levels (pretty low) up to the textbook levels specified by the display interface, such as Single-Link DVI (good for up to 1920 by 1080p). Because they have ACTIVE electrical components inside, they tend to cost about US$40 each. To support that price when competing against much cheaper adapters, ACTIVE adapters always make a point in stating ACTIVE.

You should be able to run one (and sometimes two) "legacy" displays using non-ACTIVE adapters if they are the only display you are running, or if all others are Mini DisplayPort.

To run a large Dual-Link DVI display (wider than 1920 wide) at full resolution, you need the much more expensive Apple Dual-Link DVI adapter. This adapter takes in the entire Mini DisplayPort signal and converts it to everything usually in Single_Link DVI, plus three more pairs of data lines to complete Dual -Link DVI. Its electronics are far more complex, and it runs about US$100, plus requires even more power, so it has a USB pigtail to pick up even more power.

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Answer 5

Feb 17, 2016 5:02 PM in response to tljou

There are 2 power sockets on the mother board for the graphic card. Does it matter which one i plug in?

No it does not. The 5770 gets an additional 75Watts of 12 Volt power from the aux cable plugged into that socket, and cannot operate correctly without it.

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