The Pro was 325mm2, smaller than the 350mm2 PS4 despite having double the number of CUs. they were able to double the CUs while reducing the size of the die going from 28nm to 16nm.
why wouldnt they be able to double the CUs when going from 16nm to 7nm? the zen 2 7nm cpu shouldnt take more space than the jaguar 16nm cores and even if it does, there is definitely more than enough space on the die to accomodate a 60 CU GPU and a Zen 2 along with some rtx cores.
again, 16nm to 7nm is a 2.3x increase in chip density. they should be able to put in 2.3x the Pro CUs which gives us 82 CUs on a 325mm2 chip. Or 92CUs if we also count the 4 disabled CUs on the pro. but let's ignore that and go by the actual CU count.
- we know the PS5 chip is even smaller. around 5% smaller.
- we know 36CUs take up 325mm2 on a 16nm die
- we know going to 7nm is 2.3x reduction.
- this gives us roughly a 141mm2 chip for 36CUs
- or 155mm2 chip for 40 CUs or 170 mm2 chip for 44 CUs.
so tell me, where is the rest of the 150 mm2 worth of space on the die going? are they really going to have that much room for RT cores? highly doubt that. you can look at RT cores on rtx gpus and they are around 10-20% the number of shader units. that gives us a 200mm2 chip.
so what else is in there thats taking up 111mm2 worth of space? the answer is very simple. 60-64 CUs. with 4-8 disabled you get a 56-60CU GPU at 12.9 to 13.8 tflops.
there is absolutely no reason to not use all the CUs available to you when going to 7nm. now if they wanted to settle for a cheap $399 console then they would release a 64 CU GPU at 1.0 ghz which wouldnt require cooling and give us 8 tflops. thats where all the 8 tflops rumors originated from. but now we know they are going with 1.8 ghz. potentially 1.85 ghz. there is zero reason to increase the clockspeeds so high unless they are adding in fancy vapor chamber cooling. they can get 10 tflops with 56 CUs at 1.2 ghz. so why bother going to 1.8 ghz only to settle for 40? makes zero sense.
i swear i didnt read your post before i wrote mine. i did take like half an hour to write it because my wife decided to dump both my toddlers in my room who as usual wrecked havoc all around me. it was like trying to write a forum post during the battle of the bastards.
i do love how we think alike. haha