Re: 3 simultaneous monitors (vga, dvi, hdmi onboard) with Z77 board + 3rd gen i5 3570k
Having never tried it I can't speak to the question of triple monitors being supported.
Yet in the Z77M manual you linked there are some indications that only two are supported. The manual for my Z77 Extreme6 which has four display ports, D-Sub, DVI-D, HDMI and DisplayPort echoes the same "only two' notes as the Z77M manual you linked to.
Z77M Manual, Pg 7 - Graphics
and then at the bottom of pg 26
- Three VGA Output options: D-Sub, DVI-D and HDMI (see CAUTION 6)
You can choose to use two of the three monitors only. D-Sub, DVI-D and
HDMI monitors cannot be enabled at the same time. Besides, with the
DVI-to-HDMI adapter, the DVI-D port can support the same features as
D-Sub, DVI-D and HDMI monitors cannot be enabled at the same time.
You can only choose the combination: DVI-D + HDMI, DVI-D + D-Sub,
or HDMI + D-Sub
Mine: ASRock Z77 Extreme6, i7-3770K, 16GB Samsung MV-3V4G3D/US, SeaSonic X-750 Gold, On-die HD 4000, Corsair H80i, Antec Spot Cool, Fractal Design R4 Black Pearl w/Window
Hers: ASRock 990FX Extreme4, FX-8150, 32GB AMD/Patriot AE316G1601U2K, SeaSonic X-750 Gold, Asus HD7770-2GD5, Corsair H80i, Antec Spot Cool, Fractal Design R4 Black Pearl w/Window
Server: Gigabyte GA-990FXA-UD5, FX-4170, 32GB AMD/Patriot AE316G1601U2K, Enermax ELT500AWT, IBM ServeRAID M1015, Sapphire Ultimate HD 4670, Norco RPC-470