New Crossfire Question

XxStichesxX · Dec 12, 2007, 01:26 AM

i just got 2 3850's in crossfire , everything works fine , but heres my questions i see people using 2 interconnect bridges when using 2 cards..

I.E
http://www.overclock3d.net/gfx/artic...213035437s.jpg

currently im just using 1 , but is there a differance when using 1 or 2 interconnects?

**kris23** · Dec 12, 2007, 01:55 AM

im not that familiar with crossfire but i dont think it makes much of a difference, but i think you could just bench results and see if it differs.

the 2 connectors are more for CrossfireX (4 GPUs)

you may get a bandwidth boost though if you install that 2nd bridge, just taking a guess there.

Judas · Dec 12, 2007, 02:12 AM

I raised the same question but couldn't find anyone running without the 2 of them connected.... and simply followed suit when i setup my 2x hd3870's

**ChaosMinionX** · Dec 12, 2007, 03:20 AM

You can use 1 or 2 of them, they perform identically... most people do both since they get 2 when buying crossfire setups, but in actuality you only need the 1.

Sobek · Dec 20, 2007, 06:44 PM

It really works fine if you use one bridge? I ask because I'm having a lot of problems with crossfire (I've tried everything, seriously.), and every single time, running just one bridge instead of two fixes all my corruption problems. Only thing is, it absolutely slaughters framerates. I tried it in TF2 (the one game with the most problems), and going from two bridges to one drops my fps from an average of, say, 200, to 60 or 70 (and it FEELS like 20, for some reason), these framerates are slower than with a single card. What would you suggest, powering off, removing one bridge (any one in particular?) and powering on again to let CCC detect my crossfire mode on startup?

From everything I've seen it's either great performance with 2 bridges and lots of corruption, or terrible performance with one bridge (or a single card!) and no corruption.

It seems only STALKER and Crysis work fine in Crossfire mode. I can't even get DiRT to start any more.

*edit* I read that each bridge supplies 12bit of bandwidth, and really is only needed to drive crossfire at ultra high resolutions with high bandwidth requirements (lots of AA / AF). Since I only game at 1280x1024 with 2x or at max 4xAA (anything more than that just makes things unplayable in most games), I don't see why a single bridge wouldn't be perfect.

**kris23** · Dec 20, 2007, 06:47 PM

crossfire sucks really.... the drivers are so poor that you lose performance going to 2 cards in certain games.

Dan Elliott · Jan 25, 2008, 11:52 PM

I beg to differ, I am very impressed with it. And its even improved with the 8.1's. I run COD4, Stalker, WiC, BF2, DS2 and Titan Quest all in 1680x1050 at max settings. And if you read Toms Hardware lastest on x38 chipsets you cant deny what it does in COD is impressive (last time I checked that was the game of 2007).

OldBuzzard · Jan 26, 2008, 03:47 AM

Ya gotta take Kris with a grain of salt. If it gets 1 fps less at 100000x90000 it's gonna suck, and be worthless.

Dan Elliott · Jan 26, 2008, 09:40 AM

Hey np Buzz, been a long time since I have been a member in here (maybe 12-15 years). I usually will jump into a post if I think it will will help and usually I reply to a "quip" that someone else posts even if its baseless and doesn't pertain to the topic of the originator.

But one thing about the ineternet falacies can spread quick, and to be perfectly honest I am of the opinion that Crossfire has some merit and I wouldn't want to see peoples impressions swayed by inaccurate data.

Tipstaff · Jan 26, 2008, 10:19 AM

From what an ATI tech once told me the 3800 series doesn't require both bridges to be connected, and that there is no performance difference between using 1 or both. However, he couldn't tell me if there is a benefit of having both connected outside of performance. Although logically, having both connected, wouldn't that add an extra pathway for data to be transfered back and fourth between the cards? If you are gaming at resolutions like 1900x1200 you would think that having both connectors on would help smooth things out.

In any case, as for the older series of cards, both the x1000 and x2000 series require both bridges to be connected (according to the tech). I remember with my x1950 Pros Crossfire would not work with just one bridge connected, so while I can confirm this with those cards I can't confirm it with the x2000 series.

OldBuzzard · Jan 26, 2008, 08:26 PM

It seem to me, that I read somewhere that the extra bridge was for use with 3 or more 38xx's in crossfire. I could be wrong, and at my advanced age, that is certainally a possibility

Tipstaff · Jan 26, 2008, 09:47 PM

Quote:

Originally Posted by OldBuzzard

It seem to me, that I read somewhere that the extra bridge was for use with 3 or more 38xx's in crossfire. I could be wrong, and at my advanced age, that is certainally a possibility

Nope, your right on the money, buzz, so you can relax. You aren't going senile... well, not yet anyways.

Dan Elliott · Feb 9, 2008, 12:53 AM

AS for the second interconnect, this is right from CCC:

Note: A second CrossFire interconnect cable is required to support 3D resolutions above 2560x1600 @ 60 Hz for LCD and 2048x1536 @ 66 Hz for CRTs.

That should put this question to rest

Judas · Feb 9, 2008, 02:57 PM

ah.... so i NEED it or else i wouldn't have enough juice available to power the 2560x1600 i'm running.