AMD Radeon HD 7900 to Utilize New XDR2 Rambus Memory

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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  • pbrigido
    Rambus huh...that is a tech I never thought I would see resurrected from the grave.
    29
  • burnley14
    I hope this ends up being as awesome as it sounds. I could use a GPU upgrade.
    26
  • cmaki2008
    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.
    22
  • Other Comments
  • vaughn2k
    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...
    21
  • cmaki2008
    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.
    22
  • cmaki2008
    cmaki2008Bring on the new gpus, want to replace the Gtx 480 sometime, just give me an excuse AMD! I think I like this whole predator thing, hehe.
    -21