I have a bunch of mini-Displayport to DVI adapters lying around. Some of them came from Macbooks, some came bundled with ATI video cards, and some I have no idea where they came from. How can I check if the adapters are active (converts DP to DVI signal) or passive (requires a TDMS signal, for example)? Would there be any hints or anything on the adapter that might suggest this?
An example of a specific use case: I have a Radeon 5870 Eyefinity 6 edition (6 miniDP outputs) and it only supports up to two passive DVI connections. I'm trying to figure out if one of the adapters I have is active, so that I could hook up 3 DVI monitors, without having to try out all combinations of them.