Apples and oranges. Different process, not on die.
If they had to maintain another die for edram the long term cost may well have favored using gddr5. By having it on die they can reduce cost with shrinks.
We know the 5B transistor number. We know the power budget. We know the gpu is 12CUs. ESRAM 6T fits, nothing else really does with what we know.
The Wii U 32MB is on die. Not apples and oranges. Many consoles and portables have used eDRAM, many of those used it on-die. Couple more examples are PS2 and PSP. It has a very solid console track record and makes a lot of sense in consoles.
I still do not agree that only 6T fits. It could be the answer but I think 1T could be the answer too.
Don't misunderstand me. I have made various argument about both 6T and 1T and against various incorrect information posted about both. But at this point I do not think there is enough information to say 6T for sure and 1T is out. I think the history, pros/cons and usage of 1T in consoles makes that the more likely bet. But no I would not be shocked if in the end it was 6T. But if it is 6T in the end I will not sustain arguments that old 6T SRAM (like L1/L2) is suddenly hard to do.
As far as a more powerful console than the rumors go I think the strongest argument against me is the power budget. If that 100W silent is also the maximum power then the arguments would need to center on power efficiency. I am not going to speculate on how far MS might have pushed that but I see potential if they did use 1T (since that 5B transistor count can then cover a wide range of possibilities).
Heck, Richland can use 100W with only 1.3B transistors? (Not sure if that is a dead-on transistor count.) So a 5 Billion transistor count SoC might certainly be apples and oranges compared with Richland or Temash/Kabini. PS4 might compare with Richland but I am not sure Xbox One does very well.
But I will argue for now that compared to prior consoles the size of the SoC, the size of the fan and the size of the power components (brick and buck converters) do not align with pulling a Nintendo or a weak console.
For example, comparing the 6 inductors on the Xbox One board for the SoC with the original Xbox 360 board (highest power version) you have what looks like the same number of total power components this time but they are much higher quality this time. Both the inductors and the caps are vastly better than the 360.
http://images.anandtech.com/reviews/system/microsoft/xbox360/mb.jpg
So it could be massive over engineering or perhaps we do not fully understand the power picture yet.
The 7970 GHz also uses six inductors. (The Xbox One uses five of the same type and one of a different type.)
Now before people jump all over me yes I know that there are different configurations on the 360, the One and the 7970 as far as numbers of power supplies. We are simply trying to make inferences based upon the little incomplete bits of info available. But the 7970 GHz edition is (I think) 250+ Watts. No, I am not saying 250+ Watts for Xbox One but I think it could be over 100W. (Unless that 100W silent is also the dead maximum which I think would be very unfortunate given the SoC size, cost, transistor count and potential.)
We are stuck with photos with angles, etc, but the power brick doesn't look any smaller than the original 360. (Maybe I am wrong but that is my quick guess, what do others think?)
Next look at the heatsink/fan. It has been stated it is designed to be silent at 100W. That could very well mean 100W is the maximum too. I think that would be an oddly low maximum given the $ spent on the SoC size and the size of the power brick. I think it is an oddly low maximum compared with the 360, PS3 and perhaps the PS4. I am not saying 100% that it will be different but I think there is enough questions marks to not be totally unreasonable to argue for a powerful console.
Doesn't the heatsink look rather big for a console that is pulling a Wii U 2.0 as some have put it? I looks bigger than the AMD heatsinks shipped for 140W. A fair bit bigger. Anyone else agree/disagree?
I have forgotten where the 100W was stated by MS. Can someone point me to a link so that I can review exactly what they said? And before people jump all over me I will gladly admit that I am very biased towards a powerful console.
So I think no one argued against the SoC being a record in die size/cost budget and transistor count. (In a console.)
The people who were disparaging the size of the power brick in the photos might agree that it is tied in size (with 8 years newer tech) to the 360 and perhaps is even larger and the record for a console. Not sure, anyone with a good memory of the brick sizes over the years?
The fan/heat sink might not be a record for a console. What do people think? Record, tie or smaller than the revised version for the Xbox heatsink/mounting/brittle lead free solder bump issue?
How about the power components on the Xbox One board for the SoC? Just a tie for the biggest ever in a console? (Tie with original 360, but this time the components are more capable than used in the 360?)