Crossfiring 7850 with 290x for analog out?

Enhanced Interrogator

[H]ard|Gawd
Joined
Mar 23, 2013
Messages
1,202
So I might be able to score a 290x on craigslist for a good price. I use a CRT monitor though, and the 290's have no analog output.

I think I remember reading somewhere that you can crossfire two cards from different series, but it will only give you more outputs, they won't actually crossfire (may have been bullcrap). That would be fine for what I'm trying to do, as I could use my 7850 only for its VGA output.

Anybody know anything about this?
 

Spazturtle

[H]ard|Gawd
Joined
Jan 4, 2013
Messages
1,526
Nope, 290x and 7850 use different xfire methods anyway, 7850 uses a bridge whilst the 290x uses the PCI-e bus.
 

Enhanced Interrogator

[H]ard|Gawd
Joined
Mar 23, 2013
Messages
1,202
No adapters have RAMDAC's that can hit 400mhz pixel clock like a video card can. That's why I was asking. Thanks for the answer though. I was hoping there would be some limited functionality with dissimilar cards.

I have any HDFury adapter, but the highest I could go would be around 1600x1200 @ 75hz. With resolution scaling set to max, that could still look really good, so I'm considering it.

Nope, 290x and 7850 use different xfire methods anyway, 7850 uses a bridge whilst the 290x uses the PCI-e bus.

Did not know this. So that definitely rules it out completely, thanks.
 

Xinmosni

[H]ard|Gawd
Joined
Mar 12, 2012
Messages
1,974
I think what you heard of, OP, was that you can put two completely different AMD cards in the PC and have them both recognized by Windows and be usable.

Example: ran 7970 and 5770 in my old rig. Inputs worked on both independent of one another (used 7970 for 27" 2560x1440, used 5770 for old 4:3 17").

Like others have already said, you can't crossfire them. And in fact, you don't have to, because it's not using both cards together, just both cards alongside one another.
 

Trimlock

[H]F Junkie
Joined
Sep 23, 2005
Messages
15,228
Yea, you can use one as primary then the 7850 as a secondary, just don't select crossfire in the driver (if it even let's you).
 

Xinmosni

[H]ard|Gawd
Joined
Mar 12, 2012
Messages
1,974
To clarify:

The primary and secondary cards can be used for the same extended desktop. But when you drag an application from one monitor to another, you'll see performance differences depending on which card is handling which monitor. Same thing goes for when you start a game fullscreen: the card handling that screen will be used, and the other card will only be used for whatever is on the other screen.

It's not like you'll have to have two different desktops or anything. But "Crossfire" would be using the power of two cards as if they were one. In your case, both cards will be seen separately and used for different things.
 

Enhanced Interrogator

[H]ard|Gawd
Joined
Mar 23, 2013
Messages
1,202
Interesting. You don't think there's a way to trick a game to run on the 290x but display with 7850? Something akin to the mirror the desktop option?
 

Spazturtle

[H]ard|Gawd
Joined
Jan 4, 2013
Messages
1,526
Your going to have to use the 290x for all outputs that the game is displayed on.

You should be able to use DisplayPort for your CRT monitor with an adapter. DisplayPort can do analogue output.
 
Top