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New to Crossfire - what to get to go with my old card?

Diss

Diss

Diss

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Joined
28 Oct 2002
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1,510
Hi

I have an old Saphire ATI Radeon HD 4890 Vapor-X 2048mb GDDR5 graphics card.

Am i right in thinking that with crossfire you don't need identical cards for it to work ok?

Even if this is correct any recommendations for what to best go with it - not looking for anything extreme just something reasonably priced to give me a performance boost.

HOWEVER, as this card isn't DX11 not sure it is even worth it. Could i get a brand new DX11 card for similar price/performance than if i crossfire my old card?

Thanks
 
you need 2 cards of the same family, but they will only run at the slowest models speed.
so any HD48** would work with your HD4890, but would run at the slowest cards speed.
 
What is your budget?

If you were going crossfire then you would be best to try and find another 4890 with 2gig of ram.

Your best bet though is to pick up a reasonably priced dx11 card.

it all depends on what your budget is though.
 
paradisiac said:
you need 2 cards of the same family, but they will only run at the slowest models speed.
so any HD48** would work with your HD4890, but would run at the slowest cards speed.
Click to expand...

People keep saying this but its not true. Crossfired cards run at there own individual speeds. This is true with sli but not crossfire.
 
thanks for the info guys

think i will indeed opt for a new DX11 card and put the 4890 in the back up PC
 
TheRealDeal said:
People keep saying this but its not true. Crossfired cards run at there own individual speeds. This is true with sli but not crossfire.
Click to expand...

really? sorry, i was unaware of this, its just what i was told, so kinda believed it as i had no way of really finding out. other than asking, which is what i did.
how does that work then :confused: surely if 1 card is running quicker than the other there would be issues?
 
paradisiac said:
you need 2 cards of the same family, but they will only run at the slowest models speed.
so any HD48** would work with your HD4890, but would run at the slowest cards speed.
Click to expand...

No it doesn't... This hasn't been the case for years..
The rest however is correct.

TheRealDeal said:
People keep saying this but its not true. Crossfired cards run at there own individual speeds. This is true with sli but not crossfire.
Click to expand...

Indeed, it winds me up, I point it out EVERY time lol.
 
paradisiac said:
so if both cards run independantly, does that mean my 2x1GB cards have 1GB or 2GB?
Click to expand...

The clocks can run Independent but the memory size will match that smallest available to a single GPU.

So 2x1GB Equals only 1GB effective.
 
Last edited:
I thaught with crossfire the cards ran at their own clock speeds but you were limited to the overall processing power and avalible memory of the slowest card?
 
How exactly does crossfire work then? I'd always assumed that the screen was split between the two cards, one card rendering one half, and one doing the other half. Well, not exactly half and half, but half the total number of pixels each, mixed up somehow. If one card's faster, do the drivers account for this and give the faster card a greater number of pixels to render so that they both even out, or something?
 
iviv said:
How exactly does crossfire work then? I'd always assumed that the screen was split between the two cards, one card rendering one half, and one doing the other half. Well, not exactly half and half, but half the total number of pixels each, mixed up somehow. If one card's faster, do the drivers account for this and give the faster card a greater number of pixels to render so that they both even out, or something?
Click to expand...

That would be Scissor mode which is not used any more.

AFR mode is what's used now.
 
you can pick up 4890's for £50-60

I havent missed the bonus of having DX11 at all, and have played loads of games on mates machines using it and its not a lot different,

My 4890's are still quick enough for pretty much anything at 1920x1080, DIRT3 benchmark has just given me a 51fps avg and 72fps max with ultra settings. I have yet to find anything (that is actually coded properly) that can cripple them to unplayable rates.
 
Get another 4890, Dx11 is actually a waste of time, Their are hardly any games that use Tessilation well, I regret upgrading from my 4870x2, Because i didn't really get much more performance (0 to 6%) but i lost over £250 on the 4870x2, Plus i bought a 6970 before we knew you could make the 6950 into a 6970.

Get Another 4890, Next generation we might see more Tessilation used better in Games, And cards that don't take such a massive performance hit when rendering Tessilation.

Nat.
 
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