GDDR5 memory

[jamesgoddard]

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...

 

[Malovane]

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.

 

[mactronix]

Here you go james this should answer any questions you have.
http://www.extremetech.com/article2/0,2845,2309870,00.asp
Mactronix

 

[hannibal]

Good article!

 

[TheGreatGrapeApe]

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.

 

[mactronix]

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
Mactronix