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Crossfire 4870 1GB to 512MB

Last response: in Graphics & Displays
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April 15, 2009 8:15:21 PM

Hello All,

I am hoping that someone can help me, I have done a search and the concensus is that I can crossfire a 1Gb 4870 to a 512mb.

I currently have a 512mb 4870 and am looking to buy a cheap 2nd hand 1GB 4870. The thinking is that if I come across a game that is not good with crossfire set-ups I can disable crossfire and run the 1GB 4870 on its own.

Does anyone have a similar set-up and is disabling crossfire a simply case of unticking a box in CCC or am I being naive.

Thank you in advance for your help.
a c 130 U Graphics card
April 15, 2009 8:28:24 PM

Thats fine as long as you realise that you still only have 512MB when in crossfire mode.

Mactronix
April 15, 2009 8:47:30 PM

Mactronix,

Thanks for the reply, will I get 512mb or 2x512mb in crossfire mode?
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a c 130 U Graphics card
April 15, 2009 9:31:27 PM

It dosent add up. 2 cards with 512mb give you 512mb net . If you use a 1gb card and a 512mb card you still only get 512mb.
I will try to explain.
In Crossfire you would by default be using AFR (Alternate Frame Rendering) it dosent make a differance if you use checkerboard or split screen rendering the result as far as the Ram on the cards goes is the same.
In order to calculate what it needs to do to render each frame both card needs (unfortunatly) to calculate the same information so you end up with two sets of identicle info on each card.

Mactronix
April 15, 2009 10:06:10 PM

Mac is right.

SLI or CF is not a SUM of the 2 cards RAM. Its mostly the calculating power that is "doubled".

I think your plan is not bad. With games that support CF youll have better Performance. And with games that dont youll have the 1gb. Remember that The 1gb is not really faster. read reviews about the games you play and see BENCH to know if your CF worth it or not.

Maybe it can be better for you to sell your current 4870 and buy a Single GTX285 or GTX275 ? Depand on games you play. Find benchmark !
April 15, 2009 10:17:19 PM

Thank you all for your help. With my my budget I can afford the GTX 275 which is probably the best route when I factor in heat, noise and stabilty. Thanks again.
a b U Graphics card
April 15, 2009 10:31:07 PM

Another 4870 512mb crossfired with your current one will walk all over a gtx275 in most games. What resolution are you playing at?
April 15, 2009 10:44:03 PM

1680 x 1050 - I generally play FPS and driving games.

I think you are right when CF is running well but am a little worried about heat and stabilty with my current set-up (Lian Li A17 case and HW620W PSU) thus inclined to go with a single card solution e.g. GTX 275 or HD4890.
April 16, 2009 2:07:49 AM

Depand on the games you play. If the games support CF your better with it. COD is awesome with a SLI-CF ... my SLI GTX+ was able to play COD4 and WAW maxed out, everthing to the top @ 1680x1050.

I just swapped to a single GTX285 cause GTA4 dont support SLI yet .... Now i can MAX the settings pretty well.

Your CPU is well ok for a CF.

As i told. Find reviews/benchmark of the games your playing. Try to discover if your better with a single or a CF.
!