27" Mac LED display on a 24" iMac?

[MarulaCamp]

Hey folks,

I wanted to buy a 2nd screen for my iMac, as the previous one was as dead as disco. Had a look at Apple store, and decided to go with the 27" non-thunderbolt LED.

Now, I did my homework first. Or so I thought. For this screen to work, you need a Dual Link DVI output, and a special adapter such as this one;

http://www.amazon.com/Kanex-C247DL-Inches-Display-2560x1440/dp/B005MXIK70/ref=sr_1_1?ie=UTF8

...or this one;

http://www.amazon.com/ATLONA-AT-DP400-Dual-DisplayPort-Converter/dp/B003CWEXWO/ref=pd_sim_e_2

I went with the Kanex one but first made absolutely sure I had a Dual Link DVI output. Now, my 24" iMac has a ATI Radeon 2600 Pro graphics card, which clearly states it's Dual Link DVI. See also; http://www.ehow.com/info_8164173_radeon-hd-2600-pro-specs.html
This makes sense as the 24" iMac has 1920x1200 native mode, and Single Link DVI only goes to 1600x1200.

OK, so I bought everything, hooked it up, and the max resolution I get is 1280x720. That's even lower than my previous screen (1600x1200). Pretty bummed by this.

Anyone got any tips for me?

Did Apple block the Dual Link output and should I upgrade the graphics card on my 24" iMac? What are my options, and do those options have Dual Link DVI output?

Is there perhaps a way to get more out of my current graphics card? Some system setting blocking me?

Is there anyone out there with a similar problem as me? Or perhaps someone who got this setup working?

Any help is much appreciated!

Thx,

Jochen

 

[macthefork]

Simple question... did you plug in the USB connector into the iMac, or a Powered USB hub? Those connectors require power, and that's obtained through the USB port. The resolution you're getting indicates it's not getting the full dual link signal.

 

[MarulaCamp]

Yes, the USB cable is in as well.

But in the mean time I found my problem; while the output is certainly a Dual Link DVI, somewhere in the small letters describing my Imac model, it says the maximum output is 1920Xsomething.

So basically, the specs of that Kanex kit are wrong. They say any Dual Link DVI will work, but that is NOT TRUE. You have to make very sure that your graphics card can give you the 2560Xsomething output. And as we all know, for lots of models this is not clearly specified.

 

[Zandros]

I went with the Kanex one but first made absolutely sure I had a Dual Link DVI output. Now, my 24" iMac has a ATI Radeon 2600 Pro graphics card, which clearly states it's Dual Link DVI. See also; http://www.ehow.com/info_8164173_radeon-hd-2600-pro-specs.html
This makes sense as the 24" iMac has 1920x1200 native mode, and Single Link DVI only goes to 1600x1200.

Single-link DVI supports 1920x1200. The Mini-DVI port is a miniature single-link DVI port, so it does not matter what the GPU can handle.