AMD Radeon HD 7900 to Utilize New XDR2 Rambus Memory
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 card | Radeon HD 7870 | Radeon HD 7850 | Radeon HD 7670 | Radeon HD 7570 |
|---|---|---|---|---|
| Node | TSMC 28nm HPL | TSMC 28nm HPL | TSMC 28nm HPL | TSMC 28nm HPL |
| Architecture | VLIW4 | VLIW4 | VLIW4 | VLIW4 |
| GPU | Thames XT | Thames Pro | Lombok XT | Lombok Pro |
| Radeon cluster | 24 | 22 | 12 | 12 |
| Radeon cores | 1536 | 1408 | 768 | 768 |
| GPU frequency | 950 MHz | 850 MHz | 900 MHz | 750 MHz |
| Texture units | 96 | 88 | 48 | 48 |
| ROPs | 32 | 32 | 16 | 16 |
| Graphics memory | 2GB GDDR5 | 2GB GDDR5 | 1GB GDDR5 | 1GB GDDR5 |
| Memory frequency | 5800 MHz | 5200 MHz | 5000 MHz | 4000 MHz |
| Memory interface | 256 bit | 256 bit | 128 bit | 128 bit |
| Memory bandwidth | 186 GB/s | 166 GB/s | 80 GB/s | 64 GB/s |
| Power consumption | 120 watt | 90 watt | 60 watt | 50 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 card | Radeon HD 7970 | Radeon HD 7950 | Radeon HD 6970 |
|---|---|---|---|
| Node | TSMC 28nm HP | TSMC 28nm HP | TSMC 40nm |
| Architecture | GCN | GCN | VLIW4 |
| GPU | Tahiti XT | Tahiti Pro | Cayman XT |
| Radeon cluster | 32 | 30 | 24 |
| Radeon cores | 2048 | 1920 | 1536 |
| GPU frequency | 1000 MHz | 900 MHz | 880 MHz |
| Texture units | 128 | 120 | 96 |
| ROPs | 64 | 64 | 32 |
| Graphics memory | 2GB XDR2 | 2GB XDR2 | 2GB GDDR5 |
| Memory frequency | 8000 MHz | 7200 MHz | 5500 MHz |
| Memory interface | 256 bit | 256 bit | 256 bit |
| Memory bandwidth | 256 GB/s | 230 GB/s | 176 GB/s |
| Power consumption | 190 watt | 150 watt | 250 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).



Maybe its really worth the waiting...
WAT?
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
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.
Yes. and it just can't die... no matter how you kill it...
Can't wait to see the realworld benchmarks.
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.
Do you not remember how Rambus out performed DDR back then either?