View Full Version : CrossFire doesn't work with high resolutions
Saw this on rage3d.com. Wow that's too bad it doesn't work above 1600x1200 at 60 Hz (follow the link)
http://www.rage3d.com/index.php?cat=75#newsid33828812
Serious CrossFire Limitation
Today at 02:30 PM by Ratchet
Earlier today I was given information regarding ATI’s upcoming Crossfire technology that, at first, I passed off as so ridiculous it couldn’t possibly be true. However, after having the information verified from several very reputable sources I’ve decided it would be a disservice to keep this information private.
As many are aware by now, ATI’s Crossfire technology uses an external link to connect the Master and Slave cards together (it's sort of like a 3-headed dongle with DVI connectors at the ends). What’s not generally known is that the backbone for this setup is a Silicon Image SiL 1161 chip which is installed on the X8-series Master cards. The SiL 1161 is there to receive output passed over the external link from the Slave card in the Crossfire setup and pass it on to the Master card.
Sounds decent on paper and everything, but if you check out the specs for the 1161 on this http://www.siliconimage.com/products/product.aspx?id=12&ptid=1 you will see that it is limited to single-link TMDS @ 165MHz. This means that the max 3D resolution for any X8-series Crossfire setup is 1600x1200 @ 60Hz! That means no high-res Crossfire gaming beyond 1600x1200, no 1600x1200 at a flicker free refresh rate, and no widescreen 1920x1200!
How can a technology so clearly aimed at enthusiast gamers have a limitation like this? High-resolution flicker free gaming is one of the primary benefits a multi-graphics setup like Crossfire should offer entusiasts but, somehow, ATI managed to mess that up completely.
Well, not so fast.
Single-link DVI with 165 MHz max does allow you to drive e.g. a Dell 2404fpw with its 1920x1200 just fine.
The actual practical limit will be around 2048x1536. At a lower refresh, of course.
60hz??!! I thought crossfire was supposed to be "better"
Well, not so fast.
Single-link DVI with 165 MHz max does allow you to drive e.g. a Dell 2404fpw with its 1920x1200 just fine.
The actual practical limit will be around 2048x1536. At a lower refresh, of course.
Do you want to play Half Life 2 at 45 Hz :)
GlowStick
09-15-05, 07:17 PM
Intresting notion, dose make sence from a bandwith limitation standpoint.
I refuse to believe that ATI would ship cards with this limitation. This is probably the reason for the Crossfire delay.
ATI is losing on (almost) all fronts. Their only real strong point is the AiW series.
Well, not so fast.
Single-link DVI with 165 MHz max does allow you to drive e.g. a Dell 2404fpw with its 1920x1200 just fine.
The actual practical limit will be around 2048x1536. At a lower refresh, of course.
Actually that's not true I think you are confusing a transmitter with a receiver. Transmitters could do reduced blanking to output at 1920x1200. But ATI has a receiver chip on it for their external dongle thingy.
Soooo,
please name an SLI system which can at more of 165 MHz.
While there are SLI-capable NVidia cards with dual-link DVI, did anybody ever actually use that, in SLI mode?
Soooo,
please name an SLI system which can at more of 165 MHz.
While there are SLI-capable NVidia cards with dual-link DVI, did anybody ever actually use that, in SLI mode?
I saw it working at Quakecon this year with the Dell 24 inch panels running the 7800 GTs. They were running World of Warcraft at 1920x1200 and it made my dr00l!
Is that what you mean?
Hmm i play my games @1600x1200,75Hz .. thats going to be bad if true.
still need to see what the reviewers think about it though.
I saw it working at Quakecon this year with the Dell 24 inch panels running the 7800 GTs. They were running World of Warcraft at 1920x1200 and it made my dr00l!
Is that what you mean?
No, because 1920x1200 is single-link DVI under 165 MHz, as I explained above.
Anything requiring dual-link DVI?
AthlonXP1800
09-15-05, 08:31 PM
That is very bad news, SLi is technical superior, it can allows two cards to co-operatively render images of up to 2560x1600 with 4x anti-aliasing.
GlowStick
09-15-05, 09:29 PM
Soooo,
please name an SLI system which can at more of 165 MHz.
While there are SLI-capable NVidia cards with dual-link DVI, did anybody ever actually use that, in SLI mode?Actually yes there is a forum member that reports running his 30" apple cinema monitor at native res on a pair of 6800 ultra 512mb's.
Id assume the same would work on 7800gtx's
/me switches to 1600x1200@60hz... OWW MY FRIGGIN EYES
/me switches back to 85hz... there we go :)
If the shipping xfire cards will have this limitation someone at ati is gonna be lookin for a new job. Even sli is sometimes cpu limited at 1600x1200, you gotta crank it up to 2056x1536.
Well, point taken, if NVidia does indeed support more than 1920x1200 that is that.
So I assume all you guys complaining here will throw away your 2405fpw weaklings to get Apple Cinemas displays within the next 6 months? :)
The above linked article is still severely underinformed about what single-link DVI can do.
well is it possible they could have made an updated version of the SiL 1161 before shipping to ATI?
oldsk00l
09-15-05, 11:01 PM
Soooo,
please name an SLI system which can at more of 165 MHz.
While there are SLI-capable NVidia cards with dual-link DVI, did anybody ever actually use that, in SLI mode?
I am :D
and it's sweet as hell
It looks like si has a 1171 (http://www.siliconimage.com/products/product.aspx?id=11&ptid=1) chip that can do 2048 x 1536, couldnt they simply switch to this one?
superklye
09-15-05, 11:14 PM
It looks like si has a 1171 (http://www.siliconimage.com/products/product.aspx?id=11&ptid=1) chip that can do 2048 x 1536, couldnt they simply switch to this one?
That'd probably push the r520 back another 6 months.
oldsk00l
09-15-05, 11:18 PM
It looks like si has a 1171 (http://www.siliconimage.com/products/product.aspx?id=11&ptid=1) chip that can do 2048 x 1536, couldnt they simply switch to this one?
Seriously, if it has different leads, or different voltage req's that's time ATI has to spend in re-tooling the board design/component layout.
There is no way ATI is stupid enough to release Crossfire boards with the Sil 1161 resolution limitation.
superklye
09-15-05, 11:25 PM
There is no way ATI is stupid enough to release Crossfire boards with the Sil 1161 resolution limitation.
Heh, I beg to differ.
It looks like si has a 1171 (http://www.siliconimage.com/products/product.aspx?id=11&ptid=1) chip that can do 2048 x 1536, couldnt they simply switch to this one?
They do make 2048x1536.
oldsk00l
09-16-05, 12:01 AM
There is no way ATI is stupid enough to release Crossfire boards with the Sil 1161 resolution limitation.
Just look at their crap software history, somehow their software group's incompetence contaminated their hw department.
damn shame
That is very bad news, SLi is technical superior, it can allows two cards to co-operatively render images of up to 2560x1600 with 4x anti-aliasing.
Why do you just make things up? :confused: SLI doesn't support more than one monitor.
If this news about CF is true then it's a silly move. We should see really soon how true this is.
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