I have a BenQ GW2750 27" Monitor and an Acer GR235H 23" Passive 3D monitor.
I'm not really planning to use the 3D. The monitor comes with the PC I bought.
Anyway, I have a XFX 7950 GPU with 3 ports: HDMI and 2 miniDP.
I wanted to connect use the BenQ as primary and Acer as secondary monitors. However, when I plug in the BenQ through HDMI and Acer into the miniDP using a HDMI-miniDP converter, only the BenQ works. I switched it the other way around, only the Acer works. Seems like whichever uses the HDMI port works only.