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CrossfireX - does 4 GPU's mean 4 'X2's or 4 GPU's total

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February 7, 2008 12:53:19 PM

1. I love ATI cards but trying to become educated about their technology on their site is next to impossible. I am simply trying to find out if the Crossfire X specs mean 4 GPU's "total" in a setup or can a person have 4 3870X2's in a CrossfireX setup. Is the 3870X2 seen as 1 video cards with 2 GPU's, or a single video card with the number of GPU's being transparent.

2. Followup Question for clarification is that, I heard that no interconnects(bridges) were necessary for CrossfireX - Is this true or not?


Thanks
February 7, 2008 1:14:38 PM

CrossFire X (as far as I understand) means a total of 4 GPU's is possible, maximum.
So 4 3870's, or 2 3870X2's. There will be no way to run more than 2 3870X2's in crossfire as they only have one connector on the card. Although, let's face it 4 GPU's is probably enough! :D 
Maybe if they release a refresh of the 3870X2 there will be the possibility of 4 3870X2's in crossfire...
I think AMD have really pulled something out of the bag with the 3870X2 and I am sorely tempted to chop my GTX in for one, although logic tells me another GTX would be a better idea! ;) 
February 7, 2008 1:20:59 PM

I think you can do 4 - HD3870 or 2 - 3870 X2's which was the original intent . ( pending driver support )


A 3870 X2 has 2 of the 3870 chips on one board so when you pop it in your system it is technically "crossfired". Which it is just one card so that might be where you are thinking no crossfire bridges are needed for that one card...

Pretty sure though for multiple physical cards you need those bridges or else they wouldn't provide them with the video card.....

hope that helps .. .sure others have more detailed info
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February 7, 2008 1:22:17 PM

lots of power!!!! and my power bill would probably double from 4 , x2 's ? lol........
February 8, 2008 11:29:41 AM

Thanks, I was aware that there are 2 GPU's on the 3870x2's & that they had only a single set of interconnects that was the reason for the question.

One reason was some of the newer boards coming out with 3 & 4 PCI-e slots running at x16 (PCI-e 2.0) and another was my argument with a salesman at FRY's that told me you could put 4 3870x2's in a single system using CrossfireX. He said that the interconnects were necessary in Crossfire but were not necessary in CrossfireX.

Does this remain true on the Intel chipset as well as the AMD chipset?

I want to get 2 ASUS 4DVI port 3870x2's and I was thinking possibly a single 3870. Yes I game but these are for financial charts also in my daytrading

February 8, 2008 1:05:04 PM

jnava121 said:
I think you can do 4 - HD3870 or 2 - 3870 X2's which was the original intent . ( pending driver support )


I think that's how it's supposed to work as well. I just read that the driver support for this will be released in mid march, so get ready! :) 
a c 79 U Graphics card
February 8, 2008 1:42:16 PM

And that guy at FRY's doesn't know a thing, lol
February 8, 2008 1:53:58 PM

There is only one crossfire connector on the 3870x2. Maybe with the next gen chips AMD will be able to make drivers that will allow for 8 gpus via 4 dual gpu cards.
February 8, 2008 2:05:31 PM

hcforde, to show financial charts - I'm going to assume that you want some kind of massive multi-display arrangement - you don't need to use Crossfire. You just put the cards in the slots, plug the monitors into the cards, and away you go. THG, anandtech and a bunch of other sites once showed a 10-monitor arrangement based on a gigabyte 4-slot mobo. Crossfire combines the power of multiple cards for 1 display. I'm guessing that you want multiple displays... hence you don't need to use it for your charts.

Once you do start to game, you could use the 2 3870x2's in crossfire (with the right driver), and just leave your 3870 out of it. Yeah I know - wasted horsepower - but maybe you could use the plain 3870 for physics or something.
February 8, 2008 2:13:49 PM

9/10 of the guys who work at fry's dont know **** about the department they are in and are just looking to get commission on a bigger sale. you are better off bringing a friend who knows something about electronics
February 8, 2008 3:46:49 PM

The 3870x2s don't come with any CrossFire connectors on them! So you cannot CrossFire two of them together to even get 4 GPUs.

I swear I read that somewhere...going to confirm it and fix here if it's wrong.
February 8, 2008 4:26:43 PM

they have one ...
a b U Graphics card
February 8, 2008 4:52:26 PM

The have one, and so the most you could daisy chain together with this physical limitation and current MoBos would be using 2 HD3870 in the centre and 2 HD3870X2 on the outside, thus a total of 6 VPUs.

However getting drivers to do it would be the big barrier and is the current barrier to just slapping two X2s together.
a b U Graphics card
February 8, 2008 4:54:06 PM

hcforde said:

I want to get 2 ASUS 4DVI port 3870x2's and I was thinking possibly a single 3870. Yes I game but these are for financial charts also in my daytrading


Right now they haven't mentioned support for that, but it would be possible, with the plain 3870 having to be in the middle slot.

You would just need drivers that would be able to use all 5 VPUs for gaming.
February 8, 2008 4:56:14 PM

I wonder what a system with 2 x2's will draw power wise. I've seen the charts that show total system power just under 400 watts at peak. The one thing I haven't been able to find is the cards power draw by itself so I can add it to the charts I've already seen.
February 8, 2008 7:02:19 PM

OK is there some confusion here. And is it on my part?

#1 To the best of what I can understand there is Crossfire & there is CrossfireX. To my limited knowledge they are different unless CrossfireX has been given greater enhancements and then just renamed. In any event is there a place where one can see exactly what Crossfire and CrossfireX both are and what they are suppose to do.

#2 TeraMedia - I know I do not need crossfire for financial charts - I said in the original post that I am a gamer but want this machine to do double duty ( you really can not do both simultaneously and win at either).

#3 with 4 PCI-e Slots it is feasible to have 1 3870x2 and 3 3870's and have them all inter connected if the interconnects are required. 3870x2 in slot 1 which has only 1 interconnect and cascade it down to the 3870's which all have 2 interconnects on each card for a total of 8GPU's

4 3 2 1 Card Number
I I=I=O
I=I I=I


(I) represents an interconnect on the video cards
Card number 1 is 3870x2 w/1 interconnect
Cards 2-4 are 3870's w/ 2 interconnects each

If the driver would allow and naturally on a 3 PCI-e Slot MB the max GPU possible(at this time) would be 6.

Power wise you could get by with a standard 1000W PSU. The issue of rails could be relevant as to 1 or 4-5 rails. Also I have seen external power supplies for video cards so that could be another option. "Oh the things we will do to play Crysis full-out on Vista"

In daytrading the problem with 8 monitors is that when you switch from one bank of screens to another the 2D performance has to be workstation level. Just because a card does good 3d it does not necessarilly do fast 2D. I have seen cheap $50.00 cards outrun more expensive 3d cards.

When you get into the ultra highend 3d cards the 2d performance returns. I did a comparison about a year ago. It was eye-opening.

Thanks
a b U Graphics card
February 8, 2008 7:09:00 PM

Good place to start;

http://www.crossfirex.us/

Sure that configuration is possible, but you example would provide only 5 VPUs not 8. there is no current way to do 8 without something being channelized to pcie-only without a bridge.

The most you can have physically is 6 with two of the plain 3870s in the centre and an X2 at each end, but like I said, still no confirmation of software support for that config.

For a 3 slot solution the most VPUs would be 5, one plain 3870 in the centre surrounded by two X2s.
February 8, 2008 7:46:50 PM

TheGreatGrapeApe said:
The have one, and so the most you could daisy chain together with this physical limitation and current MoBos would be using 2 HD3870 in the centre and 2 HD3870X2 on the outside, thus a total of 6 VPUs.


Daisy chain 6 VPUs together, overclock (slightly) a Phenom 9600 BE, and then try to squeeze a 2000wt PSU into the case? Try explaining all that to a fire marshall after your house burns down because of overloaded circuits.
February 8, 2008 8:08:50 PM

You can actually put a 3870x2, a 3870 or a 3850 in any combinationaslong as it doesnt go over 4gpus, tahts the limit.

So, for example, can put a 3870 with a 3850, an X2 with a 3850 even, because all use teh same core just different clocks.

As fudzilla reported with tests on there to prove it.

http://www.fudzilla.com/index.php?option=com_content&ta...

CPU bottleneck could be there but this shows that it does work and works at least quite well. Anyone who doesn't believe this just because of the so called fudzilla lies trend then you're just a grumpy old git.
February 8, 2008 8:37:34 PM

You can only have two 3870 X2's in CrossFire. Or four 3870's in CrossFireX. You do need bridges for any CrossFire configuration. But quad GPU support is not available yet. in march there will be a catalyst driver that will finnaly add support though. I think that AMD/ATi will in the future make it possible too have four 3870 X2's in CrossFireX. We will see...
a b U Graphics card
February 8, 2008 8:46:55 PM

Hat, we're talking about something diff, currently the software support limit is 4, but the hardware limit is 6, that's what we're postulating, the variability is nothing new really and the same as running the X1950XT with and X1900GT.

Anywhoo, I would love to see something similar to the E&S solution in a SIM rig.

February 8, 2008 9:56:41 PM

Of coarse you could always run xfire/sli thru the pci-e slot if it was made software possible, so I guess thats 6 for sli with GX2's and 8 on ati with 4x 3870x2s :D 
!