Mini DisplayPort to DVI-D Dual Cable/Adapter for mid-2010 iMac?

Question

Hi . . .
Sorry to pester with a question that's been covered from various angles before, but I'm new to the Mac world. Am a musician in BC, Canada doing a project remotely with people in Ontario. Decided to ditch my PC-based recording rig and went with a 2010 iMac and Logic Pro X (hallelujah!) because the other people are using Logic Pro X. So . . . I'm just learning the ropes.
Anyway . . . I have a spare monitor I want to run in dual setup extended desktop, and I'm not 100% certain of the cable and/or adapter I'll need. I'm also not sure why the adapters are bigger and seem to contain more internal components, whereas the cables just look like a simple "Plug 1" connected to "Plug 2" cable in a variety of lengths (in the same way you'd have a XLR to 1/4" phono cable).
Here's the info on my system, and any help would be greatly appreciated (will a cable suffice or do I need an separate adapter, DVI type, etc).
My iMac (mid-2010 21" Core i3 with Firewire running Moutain Lion 10.8.5):
http://www.everymac.com/systems/apple/imac/specs/imac-core-i3-3.06-21-inch-alumi num-mid-2010-specs.html
My monitor I want use as an extended desktop (Acer 22" X223W LCD):
http://reviews.cnet.com/lcd-monitors/acer-x223w-lcd-monitor/4507-3174_7-32627876 .html
So, it appears I'll need a male Mini DisplayPort to a male DVI-D Dual adapter and/or cable. Do I need to specifically buy a DVI-D Dual cable? Will a simple cable function properly or do I also need an adapter? I'm pretty sure a DVI-I cable won't work because it would have extra pins that aren't present in the DVI-D.
Thanks again . . . the assistance is appreciated.
Suds . . .

Answer 1

You are overthinking this.
"DVI dual link support" is concerned about the resolution of the display, not the number of displays.   A dual-link adapter or cable basically has double the number of wires to carry extra data to support higher resolutions than a single-link cable.  Of course, both the computer and the external display must also support the higher resolutions in order to take advantage of the capabilities of dual-link.
You want to use two displays ... your iMac's buit-in display + your Acer display as a second monitor (what you called "dual monitors").  You can do this, as I explained earlier.
Your Acer monitor's maxiumum resolution of 1680 x 1050 is not high enough to require a dual-link connection.
"In single-link mode, the maximum pixel clock frequency is 165 MHz that supports a maximum resolution of 2.75 megapixels (including blanking interval) at 60 Hz refresh. For practical purposes, this allows a maximum 16:9 screen resolution of 1920 × 1080 at 60 Hz (1915 × 1436 at a 4:3 ratio).
To support higher-resolution display devices, the DVI specification contains a provision for dual link. Dual-link DVI doubles the number of TMDS pairs, effectively doubling the video bandwidth. As a result, higher resolutions up to 2560 × 1600 are supported at 60 Hz [via dual-link DVI]."   (See Digital Visual Interface, Wikipedia)
You can connect almost any VGA, DVI or HDMI display to your iMac, using the appropriate cable and/or adapter.  Of course, you always have to make sure that your cable has the correct gender plug on each end.   The Apple adapter I recommended has a female connector, so you will need a cable with a male DVI-D plug on one end.  As for the other end of the cable, check the input on your Acer display to see what it has and select a cable that has an appropriate gender connector on the end that will plug into your Acer monitor.
In extended desktop mode, you can set separate (independent) resolutions for your iMac display and your external Acer display, taking advantage of the maximum resolution of each.   (For example, that's why the MacBookPro example you cited works, it's because that model MacBook Pro can support higher resolutions on an external display than it's built-in LCD panel can.)