Discussion – Nvidia Blackwell in Q1-2025

With Kopite7kimi pretty much confirm the 512-bit memory bus interface of upcoming Blackwell GPU, here comes the thread for discussion of all future Blackwell GPU family, aka RTX 5000 series. We also know about codename of all 5 die sizes; namely GB202, GB203, GB205, GB206 and GB207. Below is the table with some speculations of my own, you guys are welcome to pitch in:- I also put in upcoming RDNA5 just for comparison sake…

Codename Possible Model Number Possible Memory Configuration Possible Mobile GPU Possible AMD’s response
GB202 5090 Ti 512-bit 32GB
5090 448-bit 28GB
GB203 5080 Ti 384-bit 24GB N51 384-bit 24GB GDDR7
5080 320-bit 20GB N51 320-bit 20GB GDDR7
GB205 5070 Ti 256-bit 16GB 256-bit 16GB GDDR6 N52 256-bit 16GB GDDR7
GB206 5070 192-bit 12GB 192-bit 12GB GDDR6 N52 192-bit 12GB GDDR7
GB207 5060 128-bit 8/16 GB 128-bit 8GB GDDR6 N43/N44/N53 ???
5050 128-bit 8GB

Even though we know nVidia will implement 512-bit memory bus, we don’t know what types of memory they will choose, I try to list down all possibility of memory choices below:

384-bit GDDR6(X) 384-bit GDDR7 512-bit GDDR7 512-bit GDDR6X
RTX 4090 24GB 21Gbps 1TB/s 24GB 32Gbps 1.5TB/s 32GB 32Gbps 2TB/s 32GB 24Gbps 1.5TB/s
+ 50% + 100% + 50%
Pros
  • Lower TDP due to GDDR7’s lower voltage
  • Extra 50% bandwidth
  • Lower TDP due to GDDR7’s lower voltage
  • Bigger memory size
  • Double the memory bandwidth
  • Bigger memory size
  • Extra 50% bandwidth
  • Cheaper to source
Cons
  • More expensive than GDDR6x
  • Highest BOM
  • More layers PCB to accommodate 16 pcs memory chips
  • More layers PCB to accommodate 16 pcs memory chips
  • Highest TDP
AMD Radeon RX 7900 XTX 24GB 20Gbps 960GB/s 24GB 32Gbps 1.5TB/s
+ 60%

There was rumored about usage of 384-bit GDDR7 memory before, I believe nVidia is testing both 384-bit GDDR7 and 512-bit GDDR6x and then decide to use GDDR6x options. Both memories have same bandwidth even though inteface is different.

Hmm, it seems to me usage of GDDR6x make more sense compared to GDDR7, what do you think???

As for amount of CUDA cores, nVidia is changing the architecture of Blackwell GPU, so far no leaks about structure of new Shader Model…However, we should be expecting at least 50% performance improvement due to extra 50% memory bandwidth improvement…