Expect 70% performance of Geforce GTX 1080.
The rumored specs of Geforce GTX 1070 would have 2048 CUDA Cores (or Unified Shaders) is false, unfortunately. NVIDIA Geforce GTX 1070 will come with 1920 CUDA Cores (15 Streaming Multiprocessors) compared to 2560 CUDA Cores on Geforce GTX 1080. That is 25% lower than Geforce GTX 1080 CUDA Cores. Texture Mapping Unit (TMU) is reduced to 120 Units compared to 160 on Geforce GTX 1080. Render Output Units stays at 64, same as Geforce GTX 1080. By cutting down this many stream processors, NVIDIA really doesn’t want Geforce GTX 1070 to overlap Geforce GTX 1080 in terms of performance no matter how fast you overclock your card.
Other than Streaming Multiprocessors, the other things that were reduced is the boost clock, which is set to 1.6 GHz compared 1.73 GHz on Geforce GTX 1080. But you can still overclock it to squeeze more performance. The memory interface stays the same at 256 bit but the memory is still limited to GDDR5 compared to GDDR5X on Geforce GTX 1080. This will limit the memory bandwidth at 256 GB/s versus 320 GB/s on Geforce GTX 1080 which is 20% lower. Memory capacity is the same at 8 GB. It’s a good thing NVIDIA didn’t reduce that.
With that many part reduced by NVIDIA, I simply guesss Geforce GTX 1070 will perform close to 70% of Geforce GTX 1080 performance. Let’s sum everything. The reduction from CUDA Cores itself is already -25%. Then add less clock speed which will reduce the performance even further. Less memory bandwidth might contribute in reducing performance as well. In the end, the processing power is 6.5 TFLOPS compared to 9 TFLOPS on force GTX 1080. A significant reduction of 28.8% which bring us to just 72.2% processing power of Geforce GTX 1080. And the disappoint thing is the TDP only reduced to 150 Watts which is 16.6% less than Geforce GTX 1080. So, you lost 28.8% performance while saving only 16.6% on power consumption. But once we talked about the price, this is where Geforce GTX 1070 really shines. Geforce GTX 1070 MSRP is only $379 versus $599 on Geforce GTX 1080. A massive reduction of 37.7%! So, you saved 37.7% of your money and 16.6% on electricity for a performance reduction of 28.8%. Sounds like a sweet deal, eh?
Here is the comparison table I made :
|Model||Geforce GTX 1080||Geforce GTX 1070||Difference in %|
|Transistors Count||7.2 Billions||7.2 Billions|
|Boost Clock||1.73 GHz||1.6 GHz||-7.6%|
|Memory Interface||256 bit||256 bit|
|Memory Speed||10 GT/s||8 GT/s||-20.0%|
|Memory Bandwidth||320 GB/s||256 GB/s||-20.0%|
|Processing Power||9 GFLOPS||6.5 GFLOPS||-28.8%|
|TDP||180 Watts||150 Watts||-16.6%|
|Price (Founders Edition)||$699||$449||-35.6%|