HD 5870 crossfire

[jhoniedanuco]

guys i have 1 ati radeon HD5870 built in my comp. and it runs smoothly in high settings in ever game i play. i was thinking to crossfire with another HD 5870.

my question is that if two graphics card was crossfire it will add the capacity of the card like 1gb+1gb = 2gb??
or only it will add percent to boost the power of the card. and if that so how many percent most likely will be add to my card..

 

[-Fran-]

Nope, it won't the way you think. Each card will use it's own Frame Buffer depending on the needs of each chip. In other words, you will see both cards as being capable of using 1GB each, but not 2GB each since they can't share memory from the other one. Now, you will need to adress 2GB of VRAM on your system, so under that light you will need a 64bit OS if you have 2GB+ of RAM.

Cheers!

 

[Kari]

the memory doesnt add up, so if the game needs like 1,6G of memory, you are so out of luck with 1g cards (even if in crossfire)

about performance increase, read this
http://www.xbitlabs.com/articles/video/display/radeon-hd5800-crossfirex.html
but you need a very good cpu to feed the cards to get good scaling... and high rez

 

[Maziar]

SLI/CF doesn't double the memory:
http://www.tomshardware.com/forum/245454-33-crossfire-faqs
"Do SLI or CrossFire double the memory ?
This is one the questions that many people make mistake understanding it .
The answer is NO , SLI or CrossFire doesnt double the memory , You have a 512MB card , adding another card wont make your memory 1GB, it still will be 512MB,so both cards will use 512MB of RAMs but the memory won't double.
Another example :
A game needs 512MB card to run at maximum settings , and you have a 256MB card , and you think if you add another 256MB card , your memory will be 512MB and thats not true.

You may see this mistake in many sites. "

 

[jhoniedanuco]

thats what i think at first. thank you guys this is helpful..

 

[Starges]

Since SLI/CF does't double memory, wht other purpose does it serve that is greater than using a single gpu??

 

[-Fran-]

In very simple terms: a single image you would like to display on your screen will be worked on both cards as 1. That's the whole idea behind SLI and XFire.

Cheers!

 

[Starges]

So its like the thing wit multiole cores, having a task shared between 2 cores???

 

[Kari]

u'll get moar fps with xfirex/sli

 

[jhoniedanuco]

with xfire/sli adding only extra fps what can you suggest adding same card for crossfire/sli or sell that card and upgrade for the new one like 5970???

 

[Starges]

Was about to ask the same thing. Why the CF/SLi if all you get is a few extra fps??

I don't think then i would spend anothe $170 for a second 5770 if all i get is a few extra fps

 

[-Fran-]

I think you can do tri XFire with a 5970 and a 5870, actually, but you'll need a *really* big PSU for that

Anyway, the 5970 is 2x underclocked 5870's on the same PCB (board) under dedicated XFire.

Cheers!