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2 x Sapphire HD7870's, can't Crossfire

Last response: in Graphics & Displays
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February 11, 2013 11:51:37 AM

Hi, like the title says, and I'm about out of ideas.

Bought a new HD7870 today and it's the updated XT Boost model, while the other one I have is a bit older, but I can't see any reason why they won't do Crossfire. All the specs are still the same, excluding die size, texture fill rate, transistors, etc. it's still running 2Gb of GDDR5 memory on a 256bit bus with 28nm architecture. GPU name of the older one is Pitcairn and the new one is called Tahiti. Those are literally THE only differences.

I've taken some advice from other posters on here about rolling back drivers so they're not so current or the vid card won't be recognised, being too new, but the driver disk it came with has the same revision as the 13.1 drivers. I have uninstalled Catalyst, swapped cards around, the ribbon cable/bridge looks to be good, reseated everything, reinstalled, etc.

To be clear, everything is seated correctly, nothing is amiss, I can't find anything in my BIOS that could help me PCIE-wise, and I've tried various drivers and CAP updates, all to no avail.

Specs:

AMD FX-8150 (stock, no OC)
8Gb G.Skill Ripjaws
Antec Corsair 1200 PSU
ASUS Crosshair Formula V (ROG edition)
2 x Sapphire HD7870's

If anyone with any fresh ideas could reply that would be most helpful, thanks.
February 11, 2013 2:42:04 PM

I read a review on Amazon about the 7870 XT's only being able to crossifre with other XT's OR 7950...wish i could find the link but it should give u a starting point.
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February 11, 2013 2:54:13 PM

Yeah you can't crossfire the 7870 XT with a regular 7870. The XT is more like a crippled 7950.
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February 11, 2013 2:57:14 PM

The new 7870s cant crossfire with older 7870s. They can cross with 7900s though. Check out this article.
http://www.tomshardware.com/reviews/tahiti-le-7870-7930...

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February 11, 2013 8:09:47 PM

Wow what a bugger.. so much for one 78xx card pairing with another 78xx which is what I thought I could get away with.

I just tossed out my old backup card cos it wasn't being recognised at all anymore, so I guess the new backup card will be the older 7870 instead. I was going to consider a lower-grade 79xx card but costs dictate that this isn't an option, as I need a bigger case to fit everything in right now; it's very cramped in there. That, combined with the micro-stutter issue I'm likely to encounter doesn't bode well for any Crossfire solution I had planned.

Thanks for the replies anyway guys. :) 
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February 11, 2013 8:10:02 PM

Best answer selected by NorthCoastGamer.
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