I'm building my new PC, I'm focusing on ASROCK Z77 EXTREME4 and Asus P8Z77-V which has a bit better performance ( specially for multithreading).
One thing I'm concern is I'm planing to use it with 3 x DVI monitors. With the Asrock motherboard, I know it has a feature that allows use of integrated GPU in the CPU and discrete card simultaneously (I already have one PCI-E discrete card Galaxy 7600GS in my old system now and it has 1 x VGA, 1 x DVI).
I researched about the Asus mother board but can't get clear about this, Is there any one know about this feature on the Asus motherboard?
I must assume this is not for 'Gaming', IMO it best to have all digital out (DVI & Display Port), and minimally I would look at the XFX Double D FX-775A-ZDP4 Radeon HD 7750 with 2x DVI and x1 DisplayPort and if needed a DisplayPort to DVI adapter. The iGPU can support up to two monitors on SB and three monitors on IB CPUs.
You could also use the DVI with the iGPU and 2 x DVI from the above GPU, or the iGPU DVI + DisplayPort (DisplayPort to DVI adapter) + DVI from the Galaxy 7600GS.
The above should work as independent displays, and if you connect to any HDMI port from the MOBO/GPU then the onboard sound will (more than likely) be disabled and be switched through the HDMI (video + sound). You can also in this case use all of the onboard iGPU ports since the difference between digital and analog isn't important.
I know the XFX Double D FX-775A-ZDP4 Radeon HD 7750 supports (3) as stated.
I can only assume ASUS P8Z77-V (2) + 7600GS (1) = Triple Monitors, but I see no reason to think it cannot be done.
We run one to three monitors off our old HD 5770 at the office, and my daughter's gaming rig is more 'typical gaming' with 3-WAY SLI and three monitors. 99%+ of the triple monitor set-ups involve one or multiple discrete GPUs. I never use the iGPU on any system with more than (1) display.