is it stupid to crossfire with an XTX?

[BlingBlingArsch]

Title says it. XTX will clock down to XT clock rate woulnd it?

 

[Ackmed]

The XTX wont down clock, it will stay at the XTX clocks. So no, if you get a good price, I dont see why it would be dumb. Of course you could just get two XT's, and overclock them.

 

[Alaa]

SLi is better, jst take a luk at the performance of crossfire in AT's review, SLi kills it..!

 

[BlingBlingArsch]

SLI is not the topic, its about what happens when u crossfire two ATI cards of different speeds.

 

[Alaa]

how wont it clock down while the mastercard is clocked down!?? anyway if u like it, get it

 

[BroadbandGamer]

Originally posted by: Ackmed
The XTX wont down clock, it will stay at the XTX clocks. So no, if you get a good price, I dont see why it would be dumb. Of course you could just get two XT's, and overclock them.

I think you've got bad info.

XTX plus XT in Crossfire mode. Both cards will run at the XT speeds. Well, that's what I've read anyway.

 

[aatf510]

Originally posted by: BroadbandGamer

Originally posted by: Ackmed
The XTX wont down clock, it will stay at the XTX clocks. So no, if you get a good price, I dont see why it would be dumb. Of course you could just get two XT's, and overclock them.

I think you've got bad info.

XTX plus XT in Crossfire mode. Both cards will run at the XT speeds. Well, that's what I've read anyway.

That's what I read as well.

 

[Toonces]

Originally posted by: toattett

Originally posted by: BroadbandGamer

Originally posted by: Ackmed
The XTX wont down clock, it will stay at the XTX clocks. So no, if you get a good price, I dont see why it would be dumb. Of course you could just get two XT's, and overclock them.

I think you've got bad info.

XTX plus XT in Crossfire mode. Both cards will run at the XT speeds. Well, that's what I've read anyway.

That's what I read as well.

"crossfire xtx indicates that we ran a 1900 crossfire edition card in conjunction with a 1900 xtx .... this is as opposed to running the crossfire edition card in conjunction with a 1900 xt.

crossfire does not synchronize GPU speed, so performance will be (slightly) better when pairing the faster card with the crossfire. "

Posted by DerekWilson on the comments page to the X1900 review here on AT... about 1/3 of the way down.

So no, an XTX with the XT in crossfire will perform better than two XTs

 

[Avalon]

Originally posted by: UNESC0

Originally posted by: toattett

Originally posted by: BroadbandGamer

Originally posted by: Ackmed
The XTX wont down clock, it will stay at the XTX clocks. So no, if you get a good price, I dont see why it would be dumb. Of course you could just get two XT's, and overclock them.

I think you've got bad info.

XTX plus XT in Crossfire mode. Both cards will run at the XT speeds. Well, that's what I've read anyway.

That's what I read as well.

"crossfire xtx indicates that we ran a 1900 crossfire edition card in conjunction with a 1900 xtx .... this is as opposed to running the crossfire edition card in conjunction with a 1900 xt.

crossfire does not synchronize GPU speed, so performance will be (slightly) better when pairing the faster card with the crossfire. "

Posted by DerekWilson on the comments page to the X1900 review here on AT... about 1/3 of the way down.

So no, an XTX with the XT in crossfire will perform better than two XTs

What he said.

 

[Ackmed]

I believe that the X800/X850 cards were down clocked when pairing them up together. But thats no longer a problem. Which is good, mixing and matching cards could lead to a good price/performance ratio for the second card, assuming they realease a "budget" X1900 card with a low MSRP, and even lower street price.

 

[fliguy84]

now i wonder how would x1900 aiw crossfire will be like

 

[fern420]

question, if i were to build a crossfire setup and alredy have the sapphire x1900xtx would i need to make sure the master card is also a x1900xtx? and question number 2, i see some mater cards with a wierd looking plug in the place of the second dvi output, whats that all about???? i only ask because i see the saphirre brandeed master card has this weird plug on it while the other brands of master card have just a normal dvi plug in the second spot.

saphire branded with goofy plug

http://www.sapphiretech.com/en/productfiles/138image2.jpg


other brand of x1900xtx with normal plug

http://www.newegg.com/Product/Product.asp?Item=N82E16814161168

i just want to make sure if i do this i get the proper x1900xtx master card so it doesnt downclock. ohh annd where do you pickk upa crossfire cable? the only mastercard that includes one is the ati branded one but its just a x1900.

 

[Ackmed]

First off, it will not downclock no matter what.

Secondly, you need one of each of the cards you linked. The master card is the one with the "wierd looking plug", the one in the first pic. So if you already have a XTX, you need a X1900XT Crossfire Edition Card, or Master card. There are not any XTX master cards right now, not sure if there will be any later.

 

[fern420]

cool, thanks for clearing that up for me. so i would be just fine if i got this?


http://www.newegg.com/Product/Product.asp?Item=N82E16814195001


no problems mixing and matching brands?

 

[nRollo]

What's interesting about this is it doesn't even make sense when you think about it?

XTXs are faster than XTs, period. So if you're rendering every other frame, it stands to reason you can't have both outputting at their maximum speed. One would always be waiting for the other.

Same with tiling or SFR- you can't have half the screen rendered faster than the other half.

The Master card HAS to be synchronizing output, and whether the cards run at the same speed or not, the XTX Master HAS to be held back or output would be a mess.

 

[nRollo]

BTW- I would note that in the case of a X1900XT and X1900XTX, this isn't as big a deal, but there are some Crossfire mixes where this is HUGE, and I believe other ones do synch memory size and clock speed.

 

[Bobthelost]

Rollo: You're just not thinking hard enough. It would be tricky to do but you could just assign more load (1/3 and 2/3 of the screen rather than 1/2) to each card. GPU is already parralell threaded to hell and back after all. Just shift which threads are on which GPU.

 

[nRollo]

Originally posted by: Bobthelost
Rollo: You're just not thinking hard enough. It would be tricky to do but you could just assign more load (1/3 and 2/3 of the screen rather than 1/2) to each card. GPU is already parralell threaded to hell and back after all. Just shift which threads are on which GPU.

No offense, but I'm thinking fine. I realize ATIs SFR operates in this static, non dynamic fashion (a big limitation) but tiling and AFR cannot.

AFR renders every other frame, not half of the frame. So while the drivers could do a 1/3 and 2/3 split with AFR like you suggest, efficiency and performance would be greatly diminished.

Same with tiling, by definition it renders half the tiles. If they are doing what you say, and rendering fewer tiles, we're back to the net effect being the same as levelling speed- slower performance.

 

[nRollo]

In any case, any way you get there (clock speed levelling, reduced output per card, or slowed synchronization) I think the end result is the same.

An XT and an XTX can't perform as well as two XTXs, unless the drivers OC the XT to XTX speed.

 

[Bobthelost]

So in other words there could be no difference between an XTX/XT crossfire system and a XT/XT solution.

If there is then you're either wrong or they are overclocking (very unlikely if you ask me).

We got any benchmarks? Proof of the pudding is in the eating isn't it.

 

[nRollo]

Originally posted by: Bobthelost
So in other words there could be no difference between an XTX/XT crossfire system and a XT/XT solution.

If there is then you're either wrong or they are overclocking (very unlikely if you ask me).

We got any benchmarks? Proof of the pudding is in the eating isn't it.

I think it's unlikely they're OCing too. I just think the cards are close enough in performance they can synchronize without altering clock speed.

I know of no benchmarks comparing the two, but I assume you see what I mean on why it pretty much has to be that way?

That's why I never understood the whole "Crossfires ability to use different level cards is somehow a good thing" arguments.

Sure it's better than no Crossfire but it wastes card power and money to run such a rig. The X1900XT +X1900XTX and X850 XT and X850XTPE are probably he ONLY times you'd want to do this.

 

[Bobthelost]

I see what you mean, although i still sneer at your lack of imagination

Tbh you know more about the topic than i do, i'll have a look round but I don't see any fundamental reason why you couldn't do dual GPU work with dismilar cards. Could just be the way it's been implemented like in SLI. Time to read up on the topic i think.

*wanders off to work out what the heck all those TLAs were in rollos' last post*

 

[tuteja1986]

Originally posted by: Alaa
SLi is better, jst take a luk at the performance of crossfire in AT's review, SLi kills it..!

you are kidding right about sli killing crossfire... :!

 

[nRollo]

Originally posted by: Bobthelost
I see what you mean, although i still sneer at your lack of imagination

LOL fair enough. :beer:

 

[rbV5]

Originally posted by: fliguy84
now i wonder how would x1900 aiw crossfire will be like

AIW cards do not support Crossfire.