Second display not detected

[mcfx]

Hi folks,

I have the Mac Pro in my signature running my HP ZR2440w monitor on a ATI Radeon HD 5870 via DVI port. I wanted to connect my second ZR2440w monitor via the mini-display port cable but the OS doesn't detect it. Tried power cycling the monitor and unplugging the cable but nothing worked. I'm running OS X 10.6.8.

Anyone knows if there's a known errata for this?

Thanks!

 

[mcfx]

Problem fixed. Turns out detection doesn't work properly until disconnecting the primary monitor connected to the DVI port. Now it works fine.