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zeldaring said:
sc94597 said:

I mean this analysis was done already.

12SM (1536 cores) (assuming T239) just doesn't make sense on Samsung 8nm from a power-per-performance perspective. This is because the voltage-frequency curve flattens at very low frequencies (in this case <470Mhz.)

https://famiboards.com/threads/future-nintendo-hardware-technology-speculation-discussion-st-read-the-staff-posts-before-commenting.55/page-1142#post-683773

There are two things to take from the above. First, as a general point, every chip on a given manufacturing process has a peak efficiency clock, below which you lose power efficiency by reducing clocks. Secondly, we have the data from Orin to know pretty well where this point is for a GPU very similar to T239's on a Samsung 8nm process, which is around 470MHz.

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That is, if the power budget is 3W for the GPU, and the peak efficiency clock is 470MHz, and the power consumption per SM at 470MHz is 0.5W, then the best possible GPU they could include would be a 6 SM GPU running at 470MHz. Using a smaller GPU would mean higher clocks, and efficiency would drop, but using a larger GPU with lower clocks would also mean efficiency would drop, because we're already at the peak efficiency clock.

In reality, it's rare to see a chip designed to run at exactly that peak efficiency clock, because there's always a financial budget as well as the power budget. Running a smaller GPU at higher clocks means you save money, so the design is going to be a tradeoff between a desire to get as close as possible to the peak efficiency clock, which maximises performance within a fixed power budget, and as small a GPU as possible, which minimises cost. Taking the same example, another option would be to use 4 SMs and clock them at around 640MHz. This would also consume 3W, but would provide around 10% less performance. It would, however, result in a cheaper chip, and many people would view 10% performance as a worthwhile trade-off when reducing the number of SMs by 33%.

Basically 512 cores (4SM) or 768 cores (6SM) would give you better performance for the same power target, and less cost than 1536 cores (12SM), if the GPU is a T239 and if it is on Samsung 8nm. 

They talk about why Microsoft chose 6nm on the xbox x refresh for 2024 saying it was probably to save money at the 21 minute mark, and it's probably why Nintendo went with 8nm they are all about profits from day 1 they must have got a mind blowing deal.

It still doesn't make sense to use 12SM, you would use 6SM in that case and just clock up because that's even cheaper. There is no charge for clocking up whereas for actual GPU cores you are paying $$$. Microsoft has never made money on any XBox they've sold according to them so I'm not really sure if they're an example of anything. And who's to say Nintendo couldn't use 6nm TSMC either.