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Crossfire a 7950 with a 7970?

#1thompson97Posted 7/31/2013 11:44:28 PM
I heard this could be done but I've heard plenty of mixed reviews on how well it would perform. Some people say cross-firing these two cards will see the higher card(7970) clock down to the lower card(7950). While others mention that each card will perform at it's own clock speed.

Now has anyone done anything like this and has actually noticed a performance upgrade? Tell me you're pros/cons.

I'm looking for the best possible performance and I don't mind dishing out the extra 100$. Is it worth it or should I just get another 7950?

Thanks!
#2FlyinTonitePosted 7/31/2013 11:47:23 PM
Ive never heard of crossfiring 2 different cards. I know you can do different manufacturers if you have the same card but idk bout what you're trying to do
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#3Knight2520Posted 8/1/2013 12:10:50 AM(edited)
Crossfiring two different cards is possible, but IIRC they need to be the same sub-series. For example, a 7870 can't be Crossfired with a 7950. A 7970 would downclock to match the 7950.

That is, unless Crossfire has changed drastically in the last couple of years.

http://support.amd.com/us/kbarticles/Pages/AMDCrossFireFAQ.aspx
http://sites.amd.com/PublishingImages/Public/Graphic_Illustrations/WebBannerJPEG/AMD_CrossfireX_Chart_1618W.jpg
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#4myztikricePosted 8/1/2013 12:11:03 AM
So just overclock the 7950
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#5romsnbombsPosted 8/1/2013 2:00:44 AM
Knight2520 posted...
A 7970 would downclock to match the 7950.


I don't think it downclocks, it just renders frames quicker and has to 'wait' for the slower card, or the card with less shaders etc
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#6ein311Posted 8/1/2013 3:41:49 AM
romsnbombs posted...
Knight2520 posted...
A 7970 would downclock to match the 7950.


I don't think it downclocks, it just renders frames quicker and has to 'wait' for the slower card, or the card with less shaders etc

From the AMD FAQ:

What happens when graphics cards with varying memory speeds and engine clocks are paired together?

The overall performance will be adjusted to match the memory speeds and engine clocks of the lower clocked card.

Most recent compatibility matrix:
http://sites.amd.com/PublishingImages/Public/Graphic_Illustrations/WebBannerJPEG/AMD_CrossfireX_Chart_1618W.jpg
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#7KURRUPTORPosted 8/1/2013 5:11:24 AM
Get another 7950 if you wanna Xfire. Getting a 7970 will be wasteful as it will basically wind up under-clocking itself down to your 7950's speeds anyways.

Also might wanna wait to see some benches with the new 13.8 drivers because currently (or previously since 13.8 is now out I believe) Xfire was/is not very good....wound up causing more issues and actually more choppy gameplay than a single card in many/most situations.
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#8wildog2006Posted 8/1/2013 8:45:02 AM
I used to have an 5750x5770 xfire setup. It was definitely better than either card running by itself, but not as good as two 5770's. If you've got both cards, might as well do it. If you have to buy one of them, get matching cards.
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#9Knight2520Posted 8/1/2013 8:49:53 AM
From: romsnbombs | #005
I don't think it downclocks, it just renders frames quicker and has to 'wait' for the slower card, or the card with less shaders etc


Did you even read the link I posted with "CrossFireFAQ" in the URL?
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#10ein311Posted 8/1/2013 9:11:15 AM
Knight2520 posted...
Did you even read the link I posted with "CrossFireFAQ" in the URL?


I copypasta'd it and the same URL you provided in my post, just to kind of... hammer the point home. ;)
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