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Crossfire second GPU not detected

Y

YamahaAlex37

[H]ard|Gawd
Joined
Jun 23, 2005
Messages
1,775
I am trying to crossfire a 6790 with a 6850 (supposedly they will because they are both Barts, and will operate at the 6790 speed). When the 6850 is on top both cards are detected fine, however when the 6790 is on top, only the top card is detected. I wont have the crossfire bridge for another 2 days, but I would imagine Device Manager should at least detect the second card.

I want to put the 6790 on top because when the 6850 is on top it runs at 100c+ when the cards are full load, so I want to see if the same happens reversed, but so far unable to detect the 6850 when it is on the bottom.

Thanks.
 
If I can't get the 6790 working on top (which I'm not sure why), I can't decide if I should order a new motherboard with a slot in between the PCIE slots, or just watercool the top card :confused:
 
Sell both and get a single, faster card? problem solved? :) Especially since ... how much do video card water blocks cost?
 
First, the setup won't crossfire without the bridge.....
Do you have dual 8x or 16x PCI-e slots on your MB?

I also do not understand why the board won't register the two cards when the 6790 is on top?
That's odd? Maybe try and do this:
reinsert the cards, uninstall and reinstall the CCC+drivers, somethimes that's what it takes.

What %-tage do you have the fans running? stock profiles? You might want to install Trixx or Afterburner and create some custom profiles to reduce the heat up.:D
 
I thought you could only crossfire cards from the same series (i.e 6800 cards with each other only).
 
hajalie24 said:
I thought you could only crossfire cards from the same series (i.e 6800 cards with each other only).
Click to expand...

well, the theory is, the HD6790 and the HD6850 are both based on Barts, so they should be able to CF.

That being said, the:

HD4350 & 4550 can CF; HD5570 & HD5670 can; HD6500&6700, etc

Once you get higher up, what you said is true, since the performance difference and scaling of different GPU designs can get quite unwieldy.
 
macoppoli said:
You need the CROSSFIRE bridge :)
Click to expand...

I have no bridge and when the 6850 is up top the 6790 is detected just fine, not sure why the opposite does not work. Maybe the bridge will help :confused: I'll find out Thursday.

I already tried exactly what you said about the drivers magoo. I have afterburner but I'm definitely not interested in increasing the fans, in fact I can't they go to 100% really fast (100c+) and I can't stand the fan at 100%.

My idea was since the 6790 was $110, I could have crossfire most of the time and for games that had bugs I could still have good performance with the 6850. I may end up just reverting to the 6850, but I really want to figure out why this is happening first.
 
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