While I haven't as yet purchased the new Cintiq 22HD, I expect to do so in the next week or so (once I finish building my new desk).
This thread is meant to document my preparation and ultimate set-up of the 22HD on the Mac Pro as part of a 3-Monitor configuration. Hopefully it will help any others with a similar configuration by serving as an information resource, or at the very least a cautionary tale...
To begin, my configuration is as follows:
Mac Pro 3,1 (early 2008 model) 2.8 GHz Dual Quad Core Intel Xeon
ATI Radeon 5770 (Apple version)
Two 23-inch Apple Cinema Displays (ACD)
I plan on keeping my two ACD's and using the Cintiq as a third monitor. I am a graphic designer most of the time, but also do a fair amount of illustration, so the two ACD's will serve me well for the former and the Cintiq for the latter.
Issue #1: Cable Adapters
The first issue I encountered in researching a potential 3-monitor setup was the problem of cable adapters. The graphic card I purchased through Apple (ATI Radeon 5770) has two mini-DV ports and one DVI port. Since both my monitors currently have DVI connectors, I purchased an Apple mini-DisplayPort to DVI adapter for one of the monitors. This worked fine for a two monitor setup - one monitor connected directly to the DVI port, while the other used the Apple adapter to connect to the mini-DisplayPort port.
One would think that to add another DVI connected monitor, I would simply need to purchase another Apple mini-DisplayPort to DVI adapter, but this is not the case. In fact, I did just that and found that with two Apple adapters plugged in to both mini-DisplayPorts, only one monitor would work.
Upon further research I found out that Apple's adapters are PASSIVE, but ACTIVE adapters are required. I don't know why this is so (I tried to read an explanation but was frustrated by my puny artist-brain).
The good news is that mini-DisplayPort to DVI ACTIVE Adapters are available for roughly the same price as Apple's passive adapters (about $33 at this time). I ordered two of the adapters.
Last week I received my ACTIVE adapters and promptly plugged them in. I am happy to report that both Apple Cinema Displays are working perfectly via the two mini-DisplayPorts, thus leaving the DVI port free and clear for my future Cintiq 22HD purchase.
The moral of the story: Don't rely on Apple Adapters to power a 3+-monitor setup
More to come... eventually.