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crossfire memory

rallyslag

rallyslag

rallyslag

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I'm in the procces of building a new system for il2 cliffs of dover. I currently have a gainward ati 4870x2 with 2 gb of memory . As i understand it it is 2 x 1gb cards , i game at 1920 x 1200 res. What i cant understand is i have been told that my 2 gb is no better than 1 gb . I thought that the way crossfire worked meant that my card would be better at higher resolutions than the 1 gb ????

I will be partnering this with an I5 2500k , which i will o/c and 8 gb of ram. I know sims are cpu intensive , but wondering if i will have enought video memory, and as COD(cliffs of dover) is not shipping with dx11 a new card ist neccesary

So what are the facts about crossfire

Thanks:confused:
 
From what I understand when you crossfire cards, the total memory doesn't change, so if you're crossfiring 2 cards with 1GB memory, it's still 1GB and not 2GB that will be used.

Crossfiring cards will give you better performance because of the power of two cards put together, the memory doesn't have a huge impact on gaming performance from what I've seen.

The only set back is you might not be able to run some games at their total max settings because it will use more than 1GB memory, like GTA IV, I can't run everything at max because it uses way more than the 768MB memory I have at the moment.
 
Two 1gb cards in crossfire effectively have 1gb of ram (even though physically, there are 2gb).

It's due to the way they handle data. All the data is duplicated across the two sets of ram, so effectively you've got 1gb usable.

This doesn't mean your card is going to perform the same as as 1gb card. You've got 2 massively powerful gpu's in there, so you're going to get much better performance than the vast majority of 1gb cards.

My setup is the same. I've got 2x 1gb cards. When crossfired, I've effectively still only got 1gb of video memory, but my system will be much more powerful than if I was running with just a single card.
 
As i thought . Thanks for confirming .

Oh well so sticking in another 4870x2 will still leave me with 1 gb of usable ram ram even though i will actually have 4 gb. Looks like its time for a couple of 6950's :D
 
Spyke_UK said:
No, you do have 2gb of vram available on a X2 card, but as above fitting a second X2 would not give 4gb.
Click to expand...

I'm confussed again . So you are saying that a 4870x2 even though it is in affect two 1 gb cards stuck together,has two gb of availlable ram. But as has been agreed two 1 gb 4870's in crossfife gives only 1 gb of usabble ram :confused:
 
Spyke_UK said:
No, you do have 2gb of vram available on a X2 card, but as above fitting a second X2 would not give 4gb.
Click to expand...
Yes there is 2gb available, but it is 2 x 1 gb per gpu meaning that each gpu can only address 1 gb of vram. If you were to go to 6950 xfire, each gpu would have 2gb vram at its disposal.
 
2 seperate cards in crossfire will only use the vram from 1 card, as the X2 is 1 card with 2 gpu's the vram on that card can be used in full.
 
Crossfire with two 1GB cards means that each gpu has access to it's own 1GB of vram. 2x 1GB cards does not equal 2GB of vram. It's exactly the same with a dual card such as the 4870x2.
 
Hmmm, sorry for the confusion, I am indeed wrong, I had been led to believe the vram from only one pcb was used, hence my belief that the X2 was an exception.
 
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