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Best way to crossfire

Last response: in Graphics & Displays
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November 26, 2010 3:14:24 PM

Im currently runing a mixed crossfire between a 5850 and the 70, ive found that i get far better results when i use the 50 as the mastercard because it has a very large headroom for overclocking, but im unable to adjust the clocks of the 70 when in crossfire, or my system hangs

is there any way other than in CCC to adjust both manually? CCC limits the overclock so much, I tried flashing the 70 to have a higher standard clock but the asus bios seems to brick it everytime, and the msi bios was unstable

if i could get the 70 overclock with the 50 it would be really bad ass and the scaling would probably be better

More about : crossfire

December 2, 2010 1:13:56 PM

CG_Gamer,
Rule of thumb is that when crossfiring 2 cards from the same series, but different models like you are, the higher card will be dumbed down to the slowest, basically you will only go as fast as the slowest card. So in reality you are only running 5850 cf. 5850 cf is still better than a single 5870 but overclocks would be more stable with a single card. you could possibly acheive close to the same results with the single 5870 overclocked very well, and not sacrifice cooling or power. I don't know what your money situation is, but my suggestion( if you want to crossfire) is sell off the 5850 on ebay or something and try to acquire another 5870 and then proceed to blow your mind with sick FPS. Good luck. Murph
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December 2, 2010 11:24:27 PM

Well the rule of thumb definitely isnt real cus it did nothing of the sort, when you do a crossfire configuration your system automatically chooses a master gpu in which most of the rendering is done, generally its the card in the main pcie slot, the secondary gpu is then used to reinforce the main gpu, windows 7 is particularly good about this, most of the time crossfire uses afr, alternate frame rendering, where one card does even frames the other does odd or top half bottom half etc.., in a mixed gpu crossfire you cant adjust the clock of the secondary card or it makes the system unstable, instead i used the 5850 as the main gpu, overclocked the hell out of it, then i had the 5850 at oc clocks and the 5807 at regular clocks, both cards working independently of the other, and now i get performance comparable to a 5870 crossfire config
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December 3, 2010 12:25:09 AM

thats what im using, i oc my 5850 with it, but i cant adjust my 70 clocks without crashing the system
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a b K Overclocking
December 3, 2010 1:01:39 AM

Then you have 5870 version that doesn't OC too well, it's okay, OC only 5850 and let 5870 downclocking by itself, you already has a great CF setup, i'm pretty sure you can maxed out almost everything with your current setup.
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a b K Overclocking
December 3, 2010 1:09:26 AM

The 5870 can serve as the master card but first see if your 5850 can reach and remain stable at the 5870's clocks but if not you will fair well even at lower clocks so long the system isn't bottlenecked.
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December 10, 2010 3:22:02 PM

Both cards OC extremely well on there own, the 5850 surpasses 5870 clocks and performance, but when i put them together i am unable to change the clocks of the secondary car, so no matter which card is the master card i still lose peak performance, ive been using the 50 as the mastercard simply because when crossfire dsrtibutes the load 50/50 the 5850 is at par if not higher than the 5870, if i used the 5870 as the mastercard i would be stuck with the really low stock settings for the 5850, my problem is that i cant adjust the clocks of the secondary gpu
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