is quadfire even possible? [4870]

J

jamhamm

[H]ard|Gawd
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Jul 2, 2005
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if im reading the [H] review right, to crossfire two 4870's you have to bridge both connections to each other, leaving no bridge tabs for anything else...

doesnt this make it impossible to quadfire 4 4870 cards?

now 4 4850's i get - because when linking them you just use one bridge tab to another...

but the 4870?

any amd ati xfire savvy folks out there care to comment?
 
Well CrossfireX is a bit different than just Crossfire.

With 4 cards it would be connected in a sort of zig-zag pattern.

Card A would use Bridge Tab 1 on it to connect to Card B. Card B you would use Bridge Tab 2 on it to connect to Card C. Card C you would use Bridge Tab 1 on it to connect to Card D.

You would also have to have a motherboard like the MSI K9A2, due to the dual slot coolers on the 4870.

Correct me if I'm wrong, but I'm pretty sure that's right.
 
Card 1 - connect with Card 2
Card 2 - connect with Card 3
Card 3 - connect with Card 2
Card 4 - connect with Card 3

I think :eek:
 
Porter_ said:
http://www.hardforum.com/showthread.php?t=1319149
Click to expand...

yea i saw that, which is what prompted the question

if you're just xfiring two 4870's then you need to connect both bridge tabs [per the [H] review]

but if you are quadding those two with two more then you dont?

i guess that just doesn't make any sense to me - why do you have to use both tabs in the first place if you dont have to use both tabs when you add 2 more video cards...
 
Connecting both bridges isn't necessary, unless you are running at 2560x1600 res. The manual on the 3000 series says you only need one bridge up to 1920x1200.
 
i personally havent owned an ati product since my x800xl

im just going by what's in the [H] review:

As you can see, ours is an engineering sample but does reflect the full retail product. The Sapphire Radeon HD 4870 requires two 6-pin power connectors for operation. CrossFire is supported with the use of both CrossFire connectors on the video card. This means you will need a total of two CrossFire bridge connectors.
Click to expand...

from that it seems like they are saying to enable xfire for the 4870, both bridge connectors are required... maybe im reading it wrong?
 
I have tested this on my 4850. I accidentally only used ONE bridge (A1 to B1), and CrossFire was working after running tests. I later connected both bridges (A1 to B1, A2 to B2), and there was no difference. I was, however, running at 1920x1200, so I cannot confirm the above statement about going beyond that res without both bridges.

Now, I don't think what Brent_Justice said is right. The bridges are absolutely not long enough for those kinds of connections. You can fit bridges at most two slots away:
=== PCI-Ex1
||====== PCI-Ex16
=== PCI-Ex1
||====== PCI-Ex16

It just wouldn't make any sense. So, if we want to go beyond 1920x1200 with tri-fire, it isn't possible without connecting all the bridges, even though the bridges aren't long enough for it? It's all weird to me. I think you do not need both bridges if using multiple cards, but you only have two, the point isn't that you "need" both, but you already have them, so why not use them if it causes no harm.
 
Porter_ said:
http://www.hardforum.com/showthread.php?t=1319149
Click to expand...

unless I am missing something that was a dumb setup. the cards are going to have to have the same contents in memory for xfire to work. this means that they have to scale all the cards to the same speeds and so on (I guess there are modes that can work differently but I thought they didn't work well) at any rate doen't that mean that the 4870 are going to loss the all important memory bandwidth advantage over the 4850? so I am thinking that this was more like running 4 4850 instead of the 4870s. and quad gpus do not scale well right now anyways.

Then again I could be confusing this for SLI problems
 
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