HD2900XT 1GB and 512MB crossfire?

[cmdrdredd]

Can you do crossfire on a 1GB HD2900xt and a 512MB HD2900xt or do you need 2 of the same model?

Couldn't find this information anywhere.

 

[nanaki333]

no

 

[cmdrdredd]

no what? you're not very specific there :roll:

 

[BFG10K]

I thought with Crossfire you could mix-and-match RAM sizes and it would simply use the lowest common denominator?

 

[cmdrdredd]

Originally posted by: BFG10K
I thought with Crossfire you could mix-and-match RAM sizes and it would simply use the lowest common denominator?

I'd like to confirm if anyone knows for sure. I don't know how easy 1GB cards will be to come by later on. I am going to be buying a HD2900XT and I found a 1GB card used for a good price. If I could add on a 512MB card later when they are cheaper and it becomes necessary for me to have more performance in DX10 games I will do that.

However, if I need to find a 1GB card to crossfire them then I would just buy a 512MB card.

 

[nanaki333]

?Strong Points:

* Excellent performance when CrossFire is activated.
* Possibility of mixing cards of different brands and Pipes? number.
* Possibility of mixing cards with different operation frequency.
* Both cards work at 16x on PCIe, unlike the competition which do it at 8x.?

 

[bryanW1995]

who are you talking to? OP asked a specific question and you responded with an incorrect answer, then you listed some reasons why he should do what he's already decided to do.

 

[cmdrdredd]

Originally posted by: bryanW1995
who are you talking to? OP asked a specific question and you responded with an incorrect answer, then you listed some reasons why he should do what he's already decided to do.

ok all I want to know is can someone take a 1GB HD2900XT and pair it with a 512MB card for crossfire.

 

[nanaki333]

Originally posted by: bryanW1995
who are you talking to? OP asked a specific question and you responded with an incorrect answer, then you listed some reasons why he should do what he's already decided to do.

the first post in this thread i did not even know i posted. i thought i was replying to a PM. so a thousand apologies.

uhhh.. if you look at what i pasted, it answered his question, which is mixing the cards. i'm also terribly sorry that he responded while i was already in the thread trying to paste my post in (~2 minutes apart).

just doing a search on google, it looks like this question has been asked many times and the most popular answer is "yes, you can".

 

[cmdrdredd]

Originally posted by: nanaki333

Originally posted by: bryanW1995
who are you talking to? OP asked a specific question and you responded with an incorrect answer, then you listed some reasons why he should do what he's already decided to do.

the first post in this thread i did not even know i posted. i thought i was replying to a PM. so a thousand apologies.

uhhh.. if you look at what i pasted, it answered his question, which is mixing the cards. i'm also terribly sorry that he responded while i was already in the thread trying to paste my post in (~2 minutes apart).

just doing a search on google, it looks like this question has been asked many times and the most popular answer is "yes, you can".

No it has not been asked. I have been searching for 5 hours. Even an ATI tech representative on Rage3D does not know for sure but he is checking for me. His first guess was no because the 1GB card uses GDDR4 and may present difficulties in running alongside GDDR3 which may be true.

I'll wait for his response unless you can provide a link to your "google search" findings.

 

[nanaki333]

you didn't google hard enough

One note regarding using CrossFire with cards of different memory configurations is that the card with greater memory size will be capped to match the memory size of the graphics card with the least amount of memory. So there is flexibility, but with strings attached as it seems.

http://www.hardwarezone.com/ar...view.php?cid=3&id=1543
that's just the first hit from google that took me 2 minutes.

ATI's CrossFire platform allows the end user to mix graphics cards clocked differently and with various memory configurations. This means we are able to use Radeon X1900XTX, X1900XT or even lower clocked Radeon series graphics cards with the master board. It isn't widely known but you can mix and match cards from different ranges as well, as I did in an experiment before writing this article, using a X1900XTX master and X1950XTX slave. When swapping out the master card for the newer X1950 series however I ended up with a black screen when booting in windows, requiring me to reboot into VGA safe mode and deinstalling the driver, so it would be safe to assume that there may very well be a few issues if you go down this road.

http://www.driverheaven.net/re...s/x1900x1950/index.htm

another one. but yeah, i guess those are still the same memory type.

 

[cmdrdredd]

Originally posted by: nanaki333
you didn't google hard enough

One note regarding using CrossFire with cards of different memory configurations is that the card with greater memory size will be capped to match the memory size of the graphics card with the least amount of memory. So there is flexibility, but with strings attached as it seems.

http://www.hardwarezone.com/ar...view.php?cid=3&id=1543
that's just the first hit from google that took me 2 minutes.

ATI's CrossFire platform allows the end user to mix graphics cards clocked differently and with various memory configurations. This means we are able to use Radeon X1900XTX, X1900XT or even lower clocked Radeon series graphics cards with the master board. It isn't widely known but you can mix and match cards from different ranges as well, as I did in an experiment before writing this article, using a X1900XTX master and X1950XTX slave. When swapping out the master card for the newer X1950 series however I ended up with a black screen when booting in windows, requiring me to reboot into VGA safe mode and deinstalling the driver, so it would be safe to assume that there may very well be a few issues if you go down this road.

http://www.driverheaven.net/re...s/x1900x1950/index.htm

another one. but yeah, i guess those are still the same memory type.

That link is useless it just lists possibilities and is not even an actual test. I want to know for sure, not just "how it should work".

I'm still going to wait for the ATI tech to get back with me tomorrow.

That's also referring to the x850 which is many many generations old.

 

[nanaki333]

well i don't know what to tell you then if you won't believe 2 of the links i pasted. one of which where the guy says he tested an x1950 with an 1900.
http://www.techreport.com/revi...crossfire/index.x?pg=1
not that it matters, but there's something else where it says you can mix the cards with different memory configurations. even says an x1800 can mix with a slower XL.

make sure the ati tech does extensive testing before taking his word though. you wouldn't want to hear him say "how it should work".

 

[cmdrdredd]

Originally posted by: nanaki333
well i don't know what to tell you then if you won't believe 2 of the links i pasted. one of which where the guy says he tested an x1950 with an 1900.
http://www.techreport.com/revi...crossfire/index.x?pg=1
not that it matters, but there's something else where it says you can mix the cards with different memory configurations. even says an x1800 can mix with a slower XL.

make sure the ati tech does extensive testing before taking his word though. you wouldn't want to hear him say "how it should work".

That doesn't tell me anything about mixing 1GB GDDR4 with a 512MB GDDR3 card which is what I want to know about. Gimping one card to use the other is pointless really. In that case I will just grab a 512 card.

 

[nanaki333]

sorry i couldn't answer your question though (i have a couple HD2900XT 512 cards, but no 1GB GDDR4 i can use to throw in a machine and fire it up). i'm just going on the assumption that you can. if you can use cards with different pipeline configurations together (as per AMDs FAQ on crossfire), and different speeds/model (tons of google hits), i assume it would work. hopefully the AMD tech confirms the assumption and you can actually test & confirm it first hand.

 

[cmdrdredd]

According to the ATI tech you can and each card works independant however you lose the benefits of 1GB memory. So it's basically running like a 512MB card...totally not worth it.

He recommended just getting a 512card as they are much easier to find in retail channels and will probably be more prevelant as time goes on vs the 1GB.