Crossfire 3870+3850 works!

pretty sure you can crossfire with a 3870 and a 3870x2. Thats what I was planning on doing
 
Wendig0 said:
pretty sure you can crossfire with a 3870 and a 3870x2. Thats what I was planning on doing
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I'm hoping so, I would be happy to move my 8800GTS to my HTPC and bring the 3870 into my main PC.

However, the CrossfireX drivers were leaked recently, and they don't (yet) support Crossfire with these 3 GPUs.
 
rennyf77 said:
why would you want to choke off some of your 3870's performance with a 3850?
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The idea of adding a second card is to gain performance. Crossfire between non-identical cards has been working for awhile now, although it's not hyped as much. If you look at that article, there are serious performance gains with 3870-3850 Crossfire, so it's not like shooting your performance in the foot.

If AMD ever gets Crossfire X going, I may add a 3850 to my 2 3870s just for the hell of it.
 
Zinn said:
The idea of adding a second card is to gain performance. Crossfire between non-identical cards has been working for awhile now, although it's not hyped as much. If you look at that article, there are serious performance gains with 3870-3850 Crossfire, so it's not like shooting your performance in the foot.

If AMD ever gets Crossfire X going, I may add a 3850 to my 2 3870s just for the hell of it.
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sure its a gain. throwing a 3870 next to a 2900xt gives you a boost, but when some 3850 512's cost as much as 3870's, and you're not getting as much out of your dual card solution as you can, whats the point. i see it a bit like the old crossfire days when one card would reduce its performance to run with the slower card.
 
Zinn said:
it's not like that. read the article. the numbers speak for themselves.
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i did read the article. the only thing the author wrote about was that the 8.1 drivers allowed cf to work, then he posted a bunch or arbitrary benchmark numbers. so what. he should have posted cf numbers with two 3850's and compare them to the mixed cf numbers. if the numbers are within a percentage point of one another, i would say that the 3870 is leaving some performance on the card.
 
rennyf77 said:
i did read the article. the only thing the author wrote about was that the 8.1 drivers allowed cf to work, then he posted a bunch or arbitrary benchmark numbers. so what. he should have posted cf numbers with two 3850's and compare them to the mixed cf numbers. if the numbers are within a percentage point of one another, i would say that the 3870 is leaving some performance on the card.
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I think I follow your argument now.
I think you're basically saying, "Why would somebody Crossfire 3870+3850 when two 3850s likely produce very close to the same amount of performance?"
That's a valid question, and one I don't have a good answer for. Like you said, only the numbers comparing a 2x 3850 setup to a 3850/3870 setup would answer the question properly.

Does anybody know if a 256MB 3850 could be used with the 3870, and if that would reduce the 3870 down to 256MB?
 
jebo_4jc said:
The internet is hard that way
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we enthusiasts need to reign in our enthusiasm sometimes whenever a new 'thing' pops up on the radar. otherwise we're just like those mac nazi's oohing and aahing at steve jobs pulling a mac air in and out of a manila envelope. i swear, its like showing a monkey a shinny penny.
 
rennyf77 said:
i did read the article. the only thing the author wrote about was that the 8.1 drivers allowed cf to work, then he posted a bunch or arbitrary benchmark numbers. so what. he should have posted cf numbers with two 3850's and compare them to the mixed cf numbers. if the numbers are within a percentage point of one another, i would say that the 3870 is leaving some performance on the card.
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That's a good point. If we could see the difference between 2x3850 and 2x3870, the article would be a lot more useful. Sorry, I didn't really follow you at first.

I know from experience that crossfire works between two cards with different clock speeds (one of my 3870s OC's higher than the other). Since the 3850 and the 3870 run the same GPU at different speeds, there shouldn't be a problem in that respect. However, since the memory is different (512 GDDR4 vs. 256 GDDR3), that could potentially seriously limit performance. Conceivably, the 3870 would be only using half its RAM in order to communicate with the 3850 and there would be considerable difference between timings and latencies. And I wonder if there would be a difference between 3870-3850(256) Crossfire and 3870-3850(512) Crossfire... although you'd have to be a total tard to run the latter given that the 512 3850s are so closely priced to the 3870s.

Anyway, I see what you're saying, and this article fails everything except saying that mixed Crossfire doesn't NOT work.
 
tc17 said:
That is interesting. I had asked Sapphire in the past if this was possible, and they told me no, that it had to be the same model of card.
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Judging by early tests, the 3870 + 3870X2 will be a viable combo also.
 
By the time they come out with the drivers the 9800 series will be out and (rumor) the 4700 series will be 3 months away... I too planned on getting an X2 to go with my 3870 but AMD may lose a sale once I see other numbers on the 9800 series and fudzilla info on the 4700 series.

They may time themselves out of a sale, we'll see.
 
Crossfire is so much better than SLI. If only I could Crossfire Nvidia cards. Ah well.
 
rennyf77 said:
people keep saying this, but i keep not seeing it. maybe i'm missing something.
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He may be referring to the broader compatibility of Crossfire (namely, the ability to work on Intel chipsets). That's the #1 reason I'm going with Crossfire instead of SLI, because the nvidia mobos don't quite match up to the Intel ones, in general.
 
there are real differences between between the p35/x38 and 650/680 boards. the most glaring issue being incompatability issues between nvidia boards and 1333fsb cpus. the other issue is with quad core overclocking. nvidia gets dinged for the 1333 problem, but its not entirely their fault. intel's monopolistic business habits have something to with it as well. the quad core overclocking problem is nvidia's alone. there is simply no excuse. speaking of sli as a technology, there has not been an easier way to do multi gpu. for years, since the reintroduction of sli on the nv4 technology (q4, 2004), its pretty much worked out of the box. the only stumble has been the gx2. crossfire on the other was firing blanks out of the gate. the x850 crossfire card wasn't available until the nvidia 7 series rolled into the market. the x1800 crossfire card didn't appear until the nvidia started to phase out the 7800 series cards. the one and only time crossfire was comparable in performance was with the x1900 series cards. since the roll out of ati's r600 tech, cf support has been shoddy at best. i still can't cf my 3870x2's. what the fuck is up with that. tell me again why cf is better than sli?
 
jebo_4jc said:
He may be referring to the broader compatibility of Crossfire (namely, the ability to work on Intel chipsets). That's the #1 reason I'm going with Crossfire instead of SLI, because the nvidia mobos don't quite match up to the Intel ones, in general.
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Yeah, better scaling (somewhat, 3 and 4 GPU is still largely useless in most games just like Triple-SLI ), more versatile. It's the better technology to be honest. Just a shame that there isn't as much selection as to what cards you can do it with.
 
NKDietrich said:
Yeah, better scaling (somewhat, 3 and 4 GPU is still largely useless in most games just like Triple-SLI ), more versatile. It's the better technology to be honest. Just a shame that there isn't as much selection as to what cards you can do it with.
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when did it scale better than sli? during the x850, x1800, x1900, or hd 29/38 series.

more versatile? what does that mean?
 
rennyf77 said:
when did it scale better than sli? during the x850, x1800, x1900, or hd 29/38 series.

more versatile? what does that mean?
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I am referring to the current generation of cards, The 3850, 3870, and 3870X2. Generally speaking it gives a little bit better % increase per GPU than SLI does. It's not much, but its more.

More versatile:

1) Doesn't require a specific chipset or buying a chip from ATI for your motherboard to make it work.

2) You can mix and match cards in a variety of configurations, for example if someone has a 3870 (non X2) and they want to go Crossfire, they don't have to buy another 3870. They could add a 3870X2 and go with a 3 GPU setup. Or maybe they are strapped for cash and can't afford another 3870, but can afford a 3850. They can do that. With SLI you can't.

3) No artificial limits on what cards can be used. Nvidia designed Triple-SLI to only work on their highest end cards so that you can't hook up 3 8800 GT's or GTS's and get more performance for your money.
 
NKDietrich said:
I am referring to the current generation of cards, The 3850, 3870, and 3870X2. Generally speaking it gives a little bit better % increase per GPU than SLI does. It's not much, but its more.

More versatile:

1) Doesn't require a specific chipset or buying a chip from ATI for your motherboard to make it work.

2) You can mix and match cards in a variety of configurations, for example if someone has a 3870 (non X2) and they want to go Crossfire, they don't have to buy another 3870. They could add a 3870X2 and go with a 3 GPU setup. Or maybe they are strapped for cash and can't afford another 3870, but can afford a 3850. They can do that. With SLI you can't.

3) No artificial limits on what cards can be used. Nvidia designed Triple-SLI to only work on their highest end cards so that you can't hook up 3 8800 GT's or GTS's and get more performance for your money.
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i more or less agree, but are you sure the ati's scale better at the same price point? 8800gt sli produces lower frame rates than 3870 cf? anyway, thanks for the clearification.
 
rennyf77 said:
i more or less agree, but are you sure the ati's scale better at the same price point? the 8800gt sli produces lower frame rates than 3870 cf? anyway, thanks for the clearification.
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The 8800 GT SLI would probably beat out a pair of 3870s across the board, but thats because the 3870s are slower cards, not because SLI is superior to Crossfire.

ATI doesn't have a competitor to the GTS or above that isn't dependent on Crossfire though, which is their weakness. I'm not saying that ATI is the smarter purchase right now, just that Crossfire is better all around than SLI.
 
NKDietrich said:
The 8800 GT SLI would probably beat out a pair of 3870s across the board, but thats because the 3870s are slower cards, not because SLI is superior to Crossfire.

ATI doesn't have a competitor to the GTS or above that isn't dependent on Crossfire though, which is their weakness. I'm not saying that ATI is the smarter purchase right now, just that Crossfire is better all around than SLI.
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the architectures engineered by both companies are so different that you can't really compare 'similarly' performing cards. 'similarly' performing cards don't exist in this current generation. all you can go by is price point. how can you then state that cf is a better technology?
 
rennyf77 said:
the architectures engineered by both companies are so different that you can't really compare 'similarly' performing cards. 'similarly' performing cards don't exist in this current generation. all you can go by is price point. how can you then state that cf is a better technology?
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Though I don't have numbers to back it up, it seems Dietrich is arguing that adding one 3870 to another 3870 will produce a greater percentage increase than adding one GTS to another would. The GTS would still be faster, but the Radeons would be more effecient.
Again, I'm just clarifying his statements, I have no idea if it's true or not.
 
jebo_4jc said:
Though I don't have numbers to back it up, it seems Dietrich is arguing that adding one 3870 to another 3870 will produce a greater percentage increase than adding one GTS to another would. The GTS would still be faster, but the Radeons would be more effecient.
Again, I'm just clarifying his statements, I have no idea if it's true or not.
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ahhh....i see. that makes an interesting argument.
 
rennyf77 said:
oh man. i would have taken the more efficient cf argument at your word....until you linked anandtech.
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If you do not like that site, you can find some more benchmarks on your own. Several sites have done it. Anandtech was the first that came to mind and they used several games. A couple of the review I've seen only used Crysis.
 
i was under the impression that if you had two mismatched cards, the faster card would have its clock reduced to the clocks on the slower card....is this still so with crossfirex?
 
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