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Nicolas Alvargonzalez

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Message 43871 - Posted: 16 Nov 2010, 3:10:48 UTC

I have just upgraded my old 4850 with a 6850, and I was wondering if it is possible to use the 6850 to crunch Collatz, and the 4850 in the same pc to crunch MW, in Windows 7.

I might have a problem with the power supply, but I can work on that if the setup is possible.
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David Bohn

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Message 44039 - Posted: 21 Nov 2010, 22:37:36 UTC - in response to Message 43871.  

While I do not know if yours will crossfire, mine won't, I am running both a 4870 and a 3200 (in the chipset) fine together. They show up as 2 different GPUs to process tasks. There is normally only 15 seconds max in the time used for each task between the two.
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Zydor
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Message 44048 - Posted: 22 Nov 2010, 9:45:11 UTC - in response to Message 44039.  
Last modified: 22 Nov 2010, 9:46:14 UTC

You can only Crossfire cards from the same series eg both being 5XXX or both 4XXX or both 3XXX etc. Taking one card from one series and crossfire with a card from another as you are enquiring about is formally a no no. Someone on the planet has doubtless rammed in it somehow - its the way of the world - but its not designed to do it, and normally wont.

If there are issues running them as separate cards non-crossfire mode. Always worth making up a dummy plug for one - its real easy to do, there are lots of posts on the web showing how, the one Ilike best due to real clear pics of it is:

Guide to making a dummy plug

Not always necessary to use a dummy plug, but sometimes its the only way, and its handy to have that one book marked for when you find you need to. It seems strange at first sight, but its a well proven method, and very very easy to make one.

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Zy
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John Clark

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Message 44055 - Posted: 22 Nov 2010, 14:39:25 UTC

Two questions on the HD5970 ...


With an HD5970 in the primary graphics card slot (not the PCIe x16 slot) is it best to run the 2 cards in crossfire or as seperate cards/GPUs for the ATI friendly projects?

If the cards are run as separate GPUs, does the second one need a dummy plug?
Go away, I was asleep


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Zydor
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Message 44056 - Posted: 22 Nov 2010, 16:26:12 UTC - in response to Message 44055.  
Last modified: 22 Nov 2010, 16:33:27 UTC

....With an HD5970 in the primary graphics card slot (not the PCIe x16 slot) ......

With most mobos thats where its best to put the card, slot zero x16 PCIe. Not mandatory by any shape of the imagination, as for most boards and single cards even a x8 PCIe slot will cope fine even with a 5970. Its just best practice to use slot zero to aim off for future card expansion on the mobo (graphics or otherwise)

..... If the cards are run as separate GPUs, does the second one need a dummy plug?

Never yet definitively got to the bottom of that one for 5970s. Views differ, certainly at DNETC if you try running 5970 with crossfire off, and use dummy plug in a twin 5970 setup it doesnt seem to work (twin 5870 does). Anecdotally it would seem that turning off Crossfire for twin 5970 so dummy plugs can be used, also affects the card internal crossfire between the GPUs on the card. At present I've ended up running the twin 5970 Crossfire, no dummy plugs. I would prefer in the long run to use a dummy plug if I could figure a way of doing it, as it would eliminate the intra card crossfire overhead.

Regards
Zy
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R.Stanneveld

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Message 44135 - Posted: 23 Nov 2010, 22:43:19 UTC - in response to Message 44056.  
Last modified: 23 Nov 2010, 22:46:50 UTC

Not sure Zy but someone told me that switching "catalist AI" to off disables the crossfire link the 5970 uses.

Just tried it but still uses Crossfire... (damn)
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