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Will X3850 XFIRE with 1900XT ?

T

toddw

[H]ard|Gawd
Joined
Sep 9, 2004
Messages
1,455
Anyone know what cards are supported when the xfire drivers come out? I'd love to drop one of these in my aging box for instant gains.
 
i think you can only do crossfire with the same 'generation' of cards,
i.e.:

x1900 crossfire edition + any x19xx series of cards (correct me if it can't do crossfire with x1950 series)

HD 38xx series can be mixed, i.e. HD 3850 + HD 3870 or dual 3850/3870
 
the question is will a 3850 3870 combo work as 2 256m cards? or a 256 and a 512? aka will it default to 2 3850s?
 
From how I understand it only works with cards in the same generation, besides with the 2900's Crossfire became native... it's not natively supported in the older X19xx series so I doubt mixing across generations is doable.

Crossfire runs as fast as the slowest card in the combo... so a 3870 and 3850 will run like a pair of 3850's with 256 mb of memory available. Memory defaults to the lowest available on either card, so the extra 256 mb on the 3870 is just unavailable while Crossfired.
 
Digital Viper-X- said:
the question is will a 3850 3870 combo work as 2 256m cards? or a 256 and a 512? aka will it default to 2 3850s?
Click to expand...

It's only a guess, but I would bet it is prolly the latter. And even if it is the former the performance difference of a 3850+3870 combo over a 3850+3850 combo would be negligible in most modes. Especially AFR modes. Just my guess.


(The following is total supposition. An unlikely possibility. If you read into it deeply you are just being foolish. If it actually angers you then you are just being an idiot)
Of course they could prove me wrong in AFR mode by having the 3850 display it's frames at the same res bust a lower quality settings than the 3870. Not sure how that would look though. Half way between the two quality settings I would guess, as long as the frame rate stayed high enough. Below 40-60 fps or so I think it would prolly be obvious and very distracting.
 
Jalidi said:
From how I understand it only works with cards in the same generation, besides with the 2900's Crossfire became native... it's not natively supported in the older X19xx series so I doubt mixing across generations is doable.

Crossfire runs as fast as the slowest card in the combo... so a 3870 and 3850 will run like a pair of 3850's with 256 mb of memory available. Memory defaults to the lowest available on either card, so the extra 256 mb on the 3870 is just unavailable while Crossfired.
Click to expand...

I thought with CrossfireX now they give asymmetric crossfire, meaning that the 3870 shouldn't have to disable half its memory to run with the 3850, but more like run with all its memory along with the 256 on the 3850?
it confuses me too, but seems like how amd/ati is touting the technology.:confused:
 
toddw said:
Anyone know what cards are supported when the xfire drivers come out? I'd love to drop one of these in my aging box for instant gains.
Click to expand...

You could just yank out the X1900XT, plop in a 3850 512mb, and get instant fairly significant gains.

That said, no you can't Crossfire the X1900 with the 3850...the R6xx cards use an internal bridge, your X1900XT doesn't have it, and you can't use the external dongle without a master card.
 
Use the cash from selling your X1900XT and grab a second 3850. Problem solved. :)
 
while this post is now off from the original question :D I was even thinking about getting a 3850 now (still better than my x1800xt) and then adding on a 3870 X2 next year when I needed it. However, if the technology defaults to the lower that would suck so is there anyone with a link or slide showing how this newer crossfireX works? Maybe Kyle? thanks
 
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