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jamesgoddard   06-25-2008 at 02:12:39 PM

Does anyone have any more info on the GDDR5 memory being used in the 4870? It seems to be running on a 900MHz clock with 3600MHz data rate, ie quad pumped, how is this - or have ATI sent a large cheque to Rambus to license some sort of XDR technology...

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Malovane   06-25-2008 at 04:18:20 PM
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jamesgoddard wrote :

Does anyone have any more info on the GDDR5 memory being used in the 4870? It seems to be running on a 900MHz clock with 3600MHz data rate, ie quad pumped, how is this - or have ATI sent a large cheque to Rambus to license some sort of XDR technology...



This is my understanding of it, based on tidbits I've gleaned:

ATI/AMD and their partner developed the GDDR4 and GDDR5 standards. This is probably why Nvidia hasn't moved to the GDDR4/5 standards... either ATI refuses to license the technology to them, or Nvidia refuses to purchase.

Yes, it is quad pumped, which is a cheaper solution than upgrading to a 512 bit memory bus for theoretically the same bandwidth performance. Also, when GDDR5 starts heavier production, it should be cheaper to manufacture than the prior GDDR levels, giving a further advantage to ATI in any price wars the competition may consider.

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mactronix   06-25-2008 at 08:30:57 PM
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Here you go james this should answer any questions you have.
http://www.extremetech.com/article [...] 870,00.asp
Mactronix :)

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Silver Graphics badge TheGreatGrapeApe   06-25-2008 at 09:58:16 PM
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The other thing is I thin it's not quad pumped the way that DDR is double pumped / dual data rate.

From my understanding it's two 32bit words simultaneously at 8 bit per pin (instead of the one of GDDR2/3/4 at 4 bit per pin) and then double pumped.


Message edited by TheGreatGrapeApe on 06-25-2008 at 10:04:58 PM
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mactronix   06-25-2008 at 10:44:01 PM
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That would be my understanding of it also TGGA. I have read a couple of articles on it but that one was the best i have seen in my view. I would call it Quasi Quad Data Rate :D
Mactronix

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