Two 4890s in CrossfireX, add a 4650 for 2 monitors?

[nerdtalker]

I currently have a system with two 4890s in Crossfire X2, and three 24" LCDs. I originally thought that Crossfire had better multiple monitor support than SLI, however, I discovered that some of the same fundamental limitations exist (the only monitors one can use are on the card crossfire flags as "primary", and only as many connectors as that card has, which is two).

I currently would like to get one monitor setup on 4890 CrossfireX2 (so it has the maximum acceleration for gaming, e.t.c.), and a 4650 for connecting the two other monitors which won't be in crossfire at all.

I'm curious whether anybody has tried anything like this, or whether it's remotely possible from a driver level. I fear if I enable crossfire there's no way to tell it (or for it to know) to just use the two 4890s and leave the 4650 alone, but since the 4650 isn't a crossfire card, I'm erring towards it just playing nice. Anybody know? This could be related to how ATI/AMD used to want us to buy two for crossfire and then another for physics.

 

[evongugg]

Welcome to the forums!

You can undo the Crossfire and use the cards independently and hook up 3 monitors. Or if you have the third PCIe slot, you can get the 4650 and run 2 monitors off of it.

 

[evongugg]

If you add a third card, make sure your power supply is adequate.

 

[evongugg]

Open the Device Manager, and under Display Adapters you will see all three cards listed. Right-Click on the third card's entry and choose the "Disable" option. Close the Device Manager and reboot the system.

Once Vista fires back up with the third card disabled, the option to run Crossfire will show up in the Control Panel. Enable Crossfire as you normally would, and regardless of whether or not you have to reboot to enter Crossfire, once Crossfire is enabled you must reboot at least one time so that Vista starts up with Crossfire active.

Once Crossfire is enabled and Vista has been rebooted, you can open the Device Manager again and re-enable the third card.

At that point, you can do whatever you need with the other monitor(s) as you normally would. You can't extend the Crossfire rendering to the extra screens, but you can still extend the Vista Desktop, etc. and run apps or child windows as you normally would.

To get out of Crossfire, reverse the process. The key is in having the third card DISABLED while enabling or disabling Crossfire with a reboot.

 

[neon neophyte]

i really thought crossfire supported multiple monitors...

only sli is single monitor only.

... i thought.

 

[nerdtalker]

To get out of Crossfire, reverse the process. The key is in having the third card DISABLED while enabling or disabling Crossfire with a reboot.

That's exactly the kind of answer I was hoping/looking for. Excellent! That procedure completely makes sense.

 

[nerdtalker]

i really thought crossfire supported multiple monitors...

only sli is single monitor only.

... i thought.

It does, but so does SLI now. Like I said, it only supports multiple monitors up to the number of DVI ports on the card the system flags as "primary." Since I have two 4890s, and each has 2 DVI ports, the max I can run is two monitors with Crossfire turned on (and it's glitchy at that).

 

[nerdtalker]

Wanted to make a follow up post just for anyone who is interested in the future.

I got my HD4650, followed evongugg's suggestions to disable it in the device manager, enable crossfireX on the HD4890s, then enable the HD4650, and everything has worked perfectly!

I now have 3 very large monitors; the outermost two of which are driven by the $50 HD4650 which seems more than powerful enough for Aero and everything normal productivity, and the inside 24" 1920x1200 monitor driven by the two crossfire'd 4890s for gaming.

Works perfectly