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Can CF work with 4870+4850?

M

milkweg

[H]ard|Gawd
Joined
Sep 6, 2007
Messages
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I saw a post on usenet claiming you can crossfire with 3870+4850 etc. Is that true? You don't have to use identical cards ion CF like you do with Nvidia SLI? Would a 4850+4870 give you much more performance than a single 4870?
 
From my understanding, yes, but you'll will only get the speed of the lesser card (4850) not the 4870, though I'm not exactly sure how to set that up.
 
OK, thanks. Makes sense that you would only get the speed of the lesser card though so won't be bothering to do it. I'll get another 4870 if I do decide to go CF.
 
bullshhhhet

the 4870 will blaze and the 4850 will just adda bit of ummff to the main card being 4870..

if you get more 3dmarks than a stock 4870 adding a 4850 than how does it slow the 4870 down.. you just got more fps added on to the first card in gaming. !!!


so 100fps from ut3 gamewith one 4870
and 2 4870's in cf would get ya say 170 fps
adding 1 4850 + 4870 would get ya say 145 fps
 
NeonGuy said:
bullshhhhet

the 4870 will blaze and the 4850 will just adda bit of ummff to the main card being 4870..

if you get more 3dmarks than a stock 4870 adding a 4850 than how does it slow the 4870 down.. you just got more fps added on to the first card in gaming. !!!


so 100fps from ut3 gamewith one 4870
and 2 4870's in cf would get ya say 170 fps
adding 1 4850 + 4870 would get ya say 145 fps
Click to expand...

no, ATi has stated on MULTIPLE occasions that while you can crossfire 2 cards that are different, performance on the faster card will be degraded to match that of the lower performance one.......
 
But two CF 4850 cards are better than a single 4870 as long as CF works in the game, but it would make more sense to wait until you can afford another 4870.
 
ok im looking at it a diff way.

if 1 cards gets you say 10 fps in any given game. and 2 cards get you say 15fps . tou gained 5 fps. adding a nother card. so your saying im gonna get 9fps with both cards not being the same.
i just o/c my 4850 825/1200 mhz now if i add a 2nd 4850@ stock what do i get ?? both cards run a speed of stock ? tell you what i just got 16000 3dmarks on the o/cd card from 11838 marks @ stock

the only diff between the 450/4870 is faster clocks thats all.i will throw in my 2nd card in cf run a 3dmark demo and see what i get.. i will bust over 20000 thou marks.just by adding 2nd card. plus i think my overclocked card just took 10% off the lead the 4870 has over 4850. Maybey more .
 
NeonGuy said:
ok im looking at it a diff way.

if 1 cards gets you say 10 fps in any given game. and 2 cards get you say 15fps . tou gained 5 fps. adding a nother card. so your saying im gonna get 9fps with both cards not being the same.
i just o/c my 4850 825/1200 mhz now if i add a 2nd 4850@ stock what do i get ?? both cards run a speed of stock ? tell you what i just got 16000 3dmarks on the o/cd card from 11838 marks @ stock

the only diff between the 450/4870 is faster clocks thats all.i will throw in my 2nd card in cf run a 3dmark demo and see what i get.. i will bust over 20000 thou marks.just by adding 2nd card. plus i think my overclocked card just took 10% off the lead the 4870 has over 4850. Maybey more .
Click to expand...

Both cards need to be running at the same speed. Since the 4870 is significantly faster than the 4850, it will need to clock down to 4850 speeds to run in Crossfire, making the effective performance equivalent to two 4850s in Crossfire. While two 4850s do seem to be faster than a single 4870, it defeats the purpose of getting the 4870 in the first place since two 4850s could have been bought instead for a significantly lower price.

Also, please use proper spelling and punctuation in your posts. It makes them much easier to read and understand.
 
Zero82z said:
Both cards need to be running at the same speed. Since the 4870 is significantly faster than the 4850, it will need to clock down to 4850 speeds to run in Crossfire, making the effective performance equivalent to two 4850s in Crossfire. While two 4850s do seem to be faster than a single 4870, it defeats the purpose of getting the 4870 in the first place since two 4850s could have been bought instead for a significantly lower price.

Also, please use proper spelling and punctuation in your posts. It makes them much easier to read and understand.
Click to expand...

Sorry I know I am a bit out of the loop considering I have purchased Nvidia cards these last 3 gens. But I could have sworn that while what you are saying apply's SLI, I could have sworn crossfire allowed the two cards to run at different speeds and gens and models and just intelligently figured out how to balance it like taking a 3250 and 3870 you would only see at max like a 5% difference because the 3250 is so much slower. But still having the 3870 running at full speed or obviously the numbers would go down a bunch.

I think I read something about it in anandtech chipset review.

Edit:

It appears to only refer to Hybrid Crossfire which can only be done using 24xx and 34xx IGP based boards. Though I could find an actual reference on their site to whether or not one cards performance is dropped.
 
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