Can 785G + 6850 = 4 monitors?

[phaxmohdem]

The question:

Can a 785G motherboard ( MSI 785GT-E63 in this case ) be combined with another video card ( Sapphire 6870 in this case) to drive 4 monitors: 2 off of integrated, 2 from the video card?

The video card in question features dual DVI as well as two mini DisplayPort connections... so would I be better off finding some passive (active?) mini-DP to DVI adapters and running all four monitors off of one card?

I ask because the onboard video is DX 10.1 while the card is DX11, and I've had terrible luck mixing and matching cards across DX generations (granted it has been quite some time (DX9->DX10 switch) since attempting to do so)

The Background

I was fiddling around inside my PC the other day, blowing some dust bunnies out and swapping CPU coolers when I noticed that almost every capacitor on my current motherboard is beginning to bulge at the top, and one is even showing a little bit of brown crust coming through. It is an older AM2 board (ASUS M2N32-SLI Deluxe (sig)) so I'm not terribly surprised, but I'm just trying to plan ahead for a replacement in the very near future.

I want to keep my RAM (4x2GB DDR2) and CPU (PhenomII-940BE) in the event of an upgrade, but am willing to part with the video cards if need be. (Currently running an 8800GTX driving two main monitors @ 1920x1200, and an 8600GT driving two auxiliary monitors @ 1920x1080 ea.)

Since the auxiliary monitors don't do anything 3D intensive, driving them from Integrated graphics is perfectly fine... I do however need a little bit of 3D grunt for the two main work monitors.

Thoughts, suggestions? Thank you!

 

[cusideabelincoln]

I think this will depend on whether or not the motherboard you choose can drive two monitors from integrated graphics. I don't think some board can do this, as they may not offer the required connectors.

The integrated chips does support it though, according to ATI:
http://www.amd.com/us/products/desk...es/ati-radeon-hd-4200-specificatications.aspx

Two independent display controllers
Drive two displays simultaneously with independent resolutions, refresh rates, color controls and video overlays for each display
Full 30-bit display processing
Programmable piecewise linear gamma correction, color correction, and color space conversion
Spatial/temporal dithering provides 30-bit color quality on 24-bit and 18-bit displays
High quality pre- and post-scaling engines, with underscan support for all display outputs
Content-adaptive de-flicker filtering for interlaced displays
Fast, glitch-free mode switching
Hardware cursor
Two integrated DVI display outputs
Primary supports 18-, 24-, and 30-bit digital displays at all resolutions up to 1920x1200 (single-link DVI) or 2560x1600 (dual-link DVI)1
Secondary supports 18-, 24-, and 30-bit digital displays at all resolutions up to 1920x1200 (single-link DVI only)1
Each includes HDCP encoder with on-chip key storage for maximum resolution playback of protected content2

Just use AMD's Surround View to get multiple displays across discrete and integrated graphics. You will need Windows 7 or XP if you want to mix an Nvidia card with the Radeon card; Vista won't allow you to install two different video drivers. So if you have Vista you will need to pick up a Radeon card or get a board with two PCI-E x16 sized slots to continue using the 8800 and 8600 cards.

HOWEVER, I am unsure how these boards spread out the video outputs. The VGA and DVI might share a display controller or the DVI and HDMI might share a controller. I do have a motherboard with the same layout (VGA, DVI, and HDMI ports), but it would take me some time to test what it can do. If you really interested I can do it.

However you can just drive the monitors from the 6870 to take advantage of Eyefinity technology. You will need active adapters; passive won't work. Single link DVI adapters are cheaper than dual link adapters and will be enough to drive 1080p resolutions.

 

[phaxmohdem]

Thanks for the reply. Don't worry about testing it out unless you're super bored, I never considered that a motherboard could limit the combination of connectors being used :S Ideally I would be using DVI & HDMI via an HDMI -> DVI cable.

I'm not all that concerned about eyefinity functionality, as the multi-monitors are setup for productivity, not gaming (Prefer to game on a single monitor w/out bezel interference) ... plus I'm not too wild about trying to find & pay for extra adapters to make it all work. (Kind of a PITA to find a well reviewed active mini-DP to DVI adapter). Side-note: When the hell will cheaper monitors start coming with Display Port standard? It's getting a little annoying having more and more video cards that support DP, and more and more monitors standing pat with 10 year old connector sets. Something's got to give eventually.

 

[cusideabelincoln]

Eyefinity does extend beyond just gaming. AMD has implemented it for easier and more robust multi-monitor setup.

 

[Skurge]

AMD have their own single link adapters I think.

 

[Xzyrus]

I have a Gigabyte GA-MA785G-UD3H and for a short period I had a 23" LCD via DVI + 17" CRT via VGA so I doubt the VGA and DVI share a video controller. It's possible the DVI and HDMI do share the video controller like the ATI discrete cards. I don't have enough monitors with the right outputs to test out more than 2 monitors though. I've never had the need to try more than 2 monitors so that's all I can help with.

I now use a 6850 with only the 23" since the 17" was rarely used in the first place and I needed the desk space.

 

[Concillian]

The 6870 can do it on it's own right? 6850 and 6870 support 6 monitors natively. Even if your motherboard can't do it, if you're using displayport monitors, it's all just hooking up the cables.

If you need DVI or VGA, you need some adapter / hub to do it, and those devices probably don't exist or are expensive given the newness of the displayport 1.2 technology.

There's a whole page of the AT 6850 / 6870 review deidcated to how they handle multiple monitors, might want to give a look at that.