Crossfire question

[The Sauce]

Do cards need to be clocked at the same speed to run in crossfire? I have a 5850 o/c'ed to the balls. Thinking about picking up an open box for crossfire but may not be able to o/c it as well. Tks.

 

[Powermoloch]

yes, both cards need to be clocked at the same speed.

 

[Kenmitch]

Your 5850 isn't overclocked to the balls! :\

I believe it'll throttle the faster card down to the lower cards speed to answer your question.

 

[busydude]

Do cards need to be clocked at the same speed to run in crossfire?

No..crossfire can be enabled even if both cards operate at different speeds.

I believe it'll throttle the faster card down to the lower cards speed to answer your question.

No, it does not. They don't throttle down.. they just operate at their specified speeds.

 

[The Sauce]

Hmm...three responses, three different answers. One way to find out I suppose.

 

[1h4x4s3x]

Hm.. I thought so too, that the faster card will be automatically throttled down to match the slower card.

 

[betasub]

^ Responants above with crossfire systems can check for themselves.

In my experience, setting different clock speeds does not prevent crossfire. Monitoring crossfired cards with different clock speeds using GPUz does not show any throttling of the faster card's clock speed. Cards carry out their individual role by Alternate Frame Rendering (AFR).

 

[Kenmitch]

^ Responants above with crossfire systems can check for themselves.

In my experience, setting different clock speeds does not prevent crossfire. Monitoring crossfired cards with different clock speeds using GPUz does not show any throttling of the faster card's clock speed. Cards carry out their individual role by Alternate Frame Rendering (AFR).

Only one way to find out like the OP said....Guess he's gonna try

Would be kinda interesting if it would effect framerates if they run out of sync....Seems like the faster card would be waiting for the slower card to catch up anyways.

 

[apoppin]

Hm.. I thought so too, that the faster card will be automatically throttled down to match the slower card.

Not for years. You can set each clock (memory and core) separately.

SLI also allows for mixing and matching of clock speeds since last year.

Would be kinda interesting if it would effect framerates if they run out of sync....Seems like the faster card would be waiting for the slower card to catch up anyways.

i wrote a series on CrossFire scaling; PM me if you are interested in FrankenFire. It is very efficient. There is no "waiting" at all.

 

[dpodblood]

Not for years. You can set each clock (memory and core) separately.

SLI also allows for mixing and matching of clock speeds since last year.

i wrote a series on CrossFire scaling; PM me if you are interested in FrankenFire. It is very efficient. There is no "waiting" at all.

Think you could just post it here? Seems like an item of general interest. From my understanding was that it would scale down to the lower clocked card, but I was told that when xfire first came out so maybe things have changed.

 

[1h4x4s3x]

Surprising, really. Just recently I read an article about it, granted, was quite a few moons old.
/throwsoldknowledgeoverboard :thumbsup:

 

[apoppin]

Think you could just post it here? Seems like an item of general interest. From my understanding was that it would scale down to the lower clocked card, but I was told that when xfire first came out so maybe things have changed.

i have been testing CrossFireX since 2900XT days. That is when mixing and matching of cards began. i ran a 2900Pro and a 2900XT at XT speeds; i could also set the clocks independently.

i cannot post links to my own reviews and article - although anyone else can
-- AT forum rules.
()

 

[busydude]

I did my own Frankenfire review of of sorts for 5770+5750 here.. http://forums.anandtech.com/showthread.php?t=2106582&highlight=

Apponin's review is excellent though.. for anyone interested here is the link to appopin's SLI Vs. Crossfire scaling Part 1

 

[The Sauce]

Well the open box deal ran out while I was thinking it over. I was looking at the current high end vs. crossfiring my 5850. Seems the top-of-line cards get you maybe 10-15% improvement at most over what I have now. Definitely not worth $300+. What would I expect from adding on another 5850 for about $130-$150?

 

[betasub]

^ You have the set-up to handle it, and even without your big GPU overclock, 2x 5850 will get you big increases in framerates (usual disclaimers apply). That is likely to lead to you trying out all sort of different detail & AA settings until you hit the 1GB barrier. Check your case layout for dual video card cooling though!