Possible Crossfire Setup?

Just as the title says!
johnn

#1 Possible Crossfire Setup?

Post by johnn »

Having visited the ati video card page and read through there recomendations for set-up, they say same family card, same memory, and same clock speed. "Very hard for me to acquire two exact duplicate cards given my budget", I was just curious if these two 4870's I have will run crossfire in tandum. As a definite yes or no may save me a little time.

ATI saphire radeon HD 4870
1024 - video memory
750 - core clock
900 - memory clock
GDDR5

ATI radeon HD 4870
512 - video memory
770 - core clock
900 - memory clock
GDDR5

PS: If anyone has a definite yes... is there a recommended slot assignment?

Thanks again,
JohnN
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MacDitch
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#2

Post by MacDitch »

My gut feel is that the clock speeds will have to match (although you could do that by under/over-clocking I guess) but I'm afraid that I can't help you with a definitive answer. :shrug:

Hopefully someone else has more knowledge of Crossfire setup.
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sneakysaurus

#3

Post by sneakysaurus »

You probably have read this but on ATI/AMD site:
http://support.amd.com/us/kbarticles/Pa ... p_req.aspx

It says:

Q: What about the brand, clock speed and memory size?
A: You can use different brands, but always make sure to match the clock speed and memory size. It is true that if the clock speeds do not match, the faster card will match the slower clocked speed card. For best performance, matching identical cards should be used.

Not exactly good answer but seems like SLI cards with simply clock to lowest speed of pair, dont see that being an issue. ATI say "For best performance" pretty obvious this, not sure why thay say it.
johnn

#4 thanks

Post by johnn »

Thanks for the help, I'll plug and see what happens.
:wink:
After plugging the mismatched memory cards, switching slot positions
with the smaller memoried card on top, adjusting the bios to peg, setting the memory dual channel "not 100% sure if that had any effect" and making other memory timing adjustments, the cards run in tandum. Had to also reinstall the drivers for the second card's family "top card".

Gigabyte GA-MA790X-UD4P

However, now I have had to order a 2" 2X5 F to F , front panel audio cabel extension for my Scout. :oops:

So far so good? :roll:
johnn

#5

Post by johnn »

PS: Just for the sake of knowing, which I am not sure if it made any difference, the cards are double factory bridged. Oh yeah, one more thing
the second card I believe has 8x bandwidth not 16x, funny thing though,
doesn't seem to make a big difference, about 5 more mins. for collatz.
johnn

#6

Post by johnn »

Just had to say if anyone else has an idea to try this at home "I really wouldn't recommend it" because if your bios isn't tweeked right it might
mess your system up. Although I will say since AMD's aquisition of ATI
there drivers for my cards "4870's"... seem to have improved :violent1:
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