What is the result of connecting a single link (DVI-D) video source to a dual link monitor?

[Jarod Wilson]

On Oct 15, 2009, at 9:08 AM, Alex Hewitt wrote:

> Jarod Wilson wrote:
>>
>> On 10/14/2009 09:07 PM, Alex Hewitt wrote:
>>
>>> Shawn O'Shea wrote:
>>>
>>>> On Wed, Oct 14, 2009 at 5:37 PM, Alex Hewitt <hewitt_tech at comcast.net
>>>> <mailto:hewitt_tech at comcast.net>> wrote:
>>>>
>>>>     I'm trying to connect a new Mac Mini to a Barco monitor. The  
>>>> Barco
>>>>     monitor expects a dual link video source (2048 x 1536 /1536 x
>>>>     2048) but
>>>>     the Mini is outputing single link DVI-D. The Mac sees the  
>>>> monitor as
>>>>     having a resolution of 1280x1024. Apple makes a dual link DVI  
>>>> adapter
>>>>     but I don't know if this will allow the Barco to work  
>>>> properly. Anyone
>>>>     have any experience with this kind of setup?
>>>>
>>>>
>>>> Single-link DVI has less pins/wires and maxes out at 1920x1200
>>>> resolution. For higher resolutions, you need the extra wires and  
>>>> can
>>>> go to 2560x1600. You need to also make sure that the DVI cable  
>>>> you are
>>>> using is dual link as well.
>>>> Pictures of connector types:
>>>> http://www.interfacebus.com/Design_Connector_Digital_Visual_Interface_DVI_Bus.html
>>>> Discussion of single vs dual with resolution information:
>>>> "WHAT ARE SINGLE AND DUAL LINKS ?" section of
>>>> http://www.datapro.net/techinfo/dvi_info.html
>>>>
>>>> -Shawn
>>>>
>>>>     The Mac Pro does have a dual link video but I'm not sure if  
>>>> that
>>>>     system
>>>>     would also have the same problem. The Barco site only  
>>>> describes MS
>>>>     Windows systems and provides drivers for the same.
>>>>
>>>>     -Alex
>>>>
>>>>     P.S. BTW, we did connect a Totoku 3MP display (2048x1536)  
>>>> which uses a
>>>>     DVI-D connection and that display worked at full resolution.
>>>>
>>>>
>>> Thanks Shawn. Good pointers. There is something a bit odd about this
>>> though. The Totoku monitor is running at it's native resolution
>>> (2048x1536). The Mac gives me the full resolution as a choice in the
>>> display preferences. I'll look closely at the connector (miniPort to
>>> DVI-D) and see if it's actually dual link. The DVI-I dual link is
>>> definitely not working.
>>>
>>
>>  From http://www.apple.com/macmini/specs.html
>>
>> # Extended desktop and video mirroring: Simultaneously supports up to
>> 1920 by 1200 pixels on a DVI or VGA display; up to 2560 by 1600  
>> pixels
>> on a dual-link DVI display using Mini DisplayPort to Dual-Link DVI
>> Adapter (sold separately)
>>
>>
>>
> Jarod, I think you missed what I was saying.

Probably. :)

> We have a monitor running at 2048x1536 resolution. That's higher  
> than the 1900x1200 that the specs state.

I suspect Apple is playing it safe with the advertised specs. From  
what I'm looking at, single-link DVI supports up to 2.75 megapixels at  
60Hz. 1920x1200 is only 2 ((1920*1200)/(1024*1024)). Of course,  
2048x1536 is 3 megapixels though... Is that 2048x1536 by chance at  
only 50Hz? Lower refresh rate might be able to squeeze it out.

> P.S. I'm thinking of carrying the Barco monitor to the Salem Apple  
> store and hopefully the Apple folks will let me try out the dual  
> link adapter before I actually plunk down the $99 that it costs.

Yeah, don't see why they wouldn't.

> I also need to find out if the Mac Pro can drive this monitor (we  
> have several of them that we want to use).

My brother's Mac Pro has no issues driving Apple's 30" monitor at  
whatever its beefy resolution is...

-- 
Jarod Wilson
jarod at wilsonet.com