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AMD Radeon HD 7900 to Utilize New XDR2 Rambus Memory

By - Source: NordicHardware | B 118 comments

AMD is set to launch its next-generation graphic processors this coming fall and it is shaping up to be more than expected with use of XDR2 memory interface.

Based on a leaked road-map, AMD will be releasing their new GPUs in Q4 for the upcoming holiday season. The GPUs will start with four different GPUs based on the 28nm version of the VLIW4 (Very Long Instruction Word) architecture. The four GPUs will be equipped with 768 to 1536 Radeon cores (stream processors) and GDDR5 memory.

Graphics cardRadeon HD 7870Radeon HD 7850Radeon HD 7670 Radeon HD 7570
NodeTSMC 28nm HPLTSMC 28nm HPLTSMC 28nm HPLTSMC 28nm HPL
ArchitectureVLIW4VLIW4VLIW4VLIW4
GPUThames XTThames ProLombok XTLombok Pro
Radeon cluster24221212
Radeon cores15361408768768
GPU frequency950 MHz850 MHz900 MHz750 MHz
Texture units
96884848
ROPs32321616
Graphics memory
2GB GDDR52GB GDDR51GB GDDR51GB GDDR5
Memory frequency
5800 MHz5200 MHz5000 MHz4000 MHz
Memory interface
256 bit256 bit128 bit128 bit
Memory bandwidth
186 GB/s166 GB/s80 GB/s64 GB/s
Power consumption
120 watt90 watt60 watt50 watt

The fun begins when you start to look at the new high-end GPUs codenamed "Tahiti", which is expected to see a Q1 2012 release. The "Tahiti" will make use of PCIe Gen3 interface, which has a massive bandwidth of 32 GB/s. The 7900 series is set to utilizes new AMD's Graphics CoreNext GPU architecture. The GCN is expected to boost performance per square millimeter die area to improve upon the VLIW4 architecture .

The most interesting change is AMD's decision to go with XDR2 memory interface from Rambus over previous generation DDR5 memory interface. Rambus claims the XDR2 is twice as fast as DDR5, while offering 30 percent less power consumption.

Read more about Rambus' claim.

Additional information leaked has the Radeon HD 7970 series with, 2048 Radeon Cores, GPU frequency of 1000 MHz and XDR2 memory at 8000 MHz, which would result in a memory bandwidth of 256 GB/s over a 256-bit memory interface. This compared to the 176 GB/s in Radeon HD 6790 with GDDR5 memory at 5500 MHz. All this power will be packed within an estimated power consumption of 190 watts

Graphics cardRadeon HD 7970Radeon HD 7950Radeon HD 6970
NodeTSMC 28nm HPTSMC 28nm HPTSMC 40nm
ArchitectureGCNGCNVLIW4
GPUTahiti XTTahiti ProCayman XT
Radeon cluster323024
Radeon cores204819201536
GPU frequency
1000 MHz900 MHz880 MHz
Texture units
12812096
ROPs646432
Graphics memory
2GB XDR22GB XDR22GB GDDR5
Memory frequency
8000 MHz7200 MHz5500 MHz
Memory interface
256 bit256 bit256 bit
Memory bandwidth
256 GB/s230 GB/s176 GB/s
Power consumption
190 watt150 watt250 watt

There looks to be some interesting times ahead for AMD in the coming months for us to keep watch. AMD will be releasing its new "Bulldozer" architecture, along with the new GCN architecture for the 7900 series GPUs (if the information leaked is accurate).

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  • 29 Hide
    pbrigido , September 14, 2011 1:41 PM
    Rambus huh...that is a tech I never thought I would see resurrected from the grave.
  • 26 Hide
    burnley14 , September 14, 2011 1:24 PM
    I hope this ends up being as awesome as it sounds. I could use a GPU upgrade.
  • 22 Hide
    cmaki2008 , September 14, 2011 1:20 PM
    Bring on the new gpus, want to replace the Gtx 480 sometime, just give me an excuse AMD! I think I like this whole Preditor thing, hehe.
Other Comments
  • 21 Hide
    vaughn2k , September 14, 2011 1:18 PM
    Maybe this would also be the technology aligned with the third generation APU, where cores and instruction sets are heterogenous with the CPU...
    Maybe its really worth the waiting...
  • 22 Hide
    cmaki2008 , September 14, 2011 1:20 PM
    Bring on the new gpus, want to replace the Gtx 480 sometime, just give me an excuse AMD! I think I like this whole Preditor thing, hehe.
  • 26 Hide
    burnley14 , September 14, 2011 1:24 PM
    I hope this ends up being as awesome as it sounds. I could use a GPU upgrade.
  • 8 Hide
    msgun98 , September 14, 2011 1:30 PM
    I'm really looking forward to some benchmarks for these. Even moreso than Bulldozer.
  • 14 Hide
    happyballz , September 14, 2011 1:34 PM
    So since RAMBUS got taken over by Apple as the lead patent troll they are now actually starting to make something? About time! I did like their memory for p4 line back in the day but cost was astronomical; I hope this isn't going to be the case where memory will cost 80% of the card and make it too costly. Wait and see I guess.
  • 3 Hide
    crazybernie , September 14, 2011 1:38 PM
    Get that dirty Rambus away from my AMD GPU.
  • 29 Hide
    pbrigido , September 14, 2011 1:41 PM
    Rambus huh...that is a tech I never thought I would see resurrected from the grave.
  • 15 Hide
    borden5 , September 14, 2011 1:42 PM
    aww such a tease hd 7xxx come to daddy pls
  • 5 Hide
    Filiprino , September 14, 2011 1:45 PM
    happyballzSo since RAMBUS got taken over by Apple as the lead patent troll they are now actually starting to make something? About time! I did like their memory for p4 line back in the day but cost was astronomical; I hope this isn't going to be the case where memory will cost 80% of the card and make it too costly. Wait and see I guess.


    Cost astronomical and implementation stupid. You needed two modules, the terminating module and the normal module. That was in a world where multiple channel memory systems still didn't exist.
    If this XDR2 lives up to what promises it will break a lot of banks :p 
    Now AMD has to bring support for dual GPU cards on their AMD APP SDK and an HD 7990 would
    make wonders on number crunching tasks.
  • 9 Hide
    vaughn2k , September 14, 2011 1:45 PM
    pbrigidoRambus huh...that is a tech I never thought I would see resurrected from the grave.

    Yes. and it just can't die... no matter how you kill it...
  • 12 Hide
    xtremeways , September 14, 2011 1:46 PM
    screw RAMBUS!..does anyone remember how they bad hurt memory the industry about 10 years back suing all the memory manufacturers?.. Then not to mention the BS ram that was on intel motherboards about the same time. I will never buy anything with Rambus on board
  • 6 Hide
    dark_lord69 , September 14, 2011 1:48 PM
    Seems like these new video cards may have impressive performance.
    Can't wait to see the realworld benchmarks.
  • 11 Hide
    silverblue , September 14, 2011 1:50 PM
    Yeah yeah, of course Rambus would say that. They argued that DDR was inferior when it wasn't... but I'm happy to give them a second chance this time around.

    Notice the change in ratio of texture units:ROPs from 3:1 in the 6970 and 7870 to 2:1 in the 7950 and 7970? Put simply, the 7970 is a sizeable improvement over the 6970 before we even look at memory bandwidth.
  • 5 Hide
    meat81 , September 14, 2011 1:55 PM
    xtremewaysscrew RAMBUS!..does anyone remember how they bad hurt memory the industry about 10 years back suing all the memory manufacturers?.. Then not to mention the BS ram that was on intel motherboards about the same time. I will never buy anything with Rambus on board


    Do you not remember how Rambus out performed DDR back then either?
  • 3 Hide
    Maziar , September 14, 2011 1:56 PM
    hmm,looks really interesting. Can't wait for benchies
  • 8 Hide
    obgbeto , September 14, 2011 1:59 PM
    It looks like its time to upgrade from my 4870 512MB to that 7980 2GB for battle file 3 :) 
  • 3 Hide
    Chainzsaw , September 14, 2011 2:01 PM
    7850 looks like the best deal.
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