I want to connect two 2560x1440 displays to a summer 2012 MacBook Pro Retina (MBP from now on). The best way to do it would be to buy two Apple thunderbolt displays, which would connect
Display2 → Thunderbolt → Display1 → Thunderbolt → MacBookPro
Unfortunately, those displays are too expensive, and I want to get two of the same 2560x1440 IPS displays by a cheaper maker, for 1/3 price, as described here:
CodingHorror: The IPS LCD Revolution
These displays connect over Dual-Link-DVI. The latest MBP has two Thunderbolt ports which should act as Mini-DisplayPorts, and I could theoretically just buy two Mini-DisplayPort → Dual-link-DVI adapters from Apple.
This adapter also uses a USB port. Apparently it's meant to provide additional power to the MBP in order for the display not to flicker.
Is this really necessary? The Apple product questions (>100 of them) have a single answer that touches on this and it says it "may be needed"? Is it necessary only when the MBP is on battery, or even when it's plugged in?
Why would a display's digital signal be using so much power? This MBP has two Thunderbolt ports.
Given all that:
Is it possible to add a display (using an adapter) to each of the two Thunderbolt ports for a total of 3 displays (1 internal, 2 externals)? Some video cards only support two displays, even though they have more ports.
Or is there a Thunderbolt → Dual Dual-Link DVI adapter of any kind? If I were to purchase Apple's Thunderbolt displays I could just connect everything over a single Thunderbolt port.