I wouldn't call it on a whim, businesses like theirs have to make investments, and having a base to start from is important, MS did originally use nearly off the shelf parts for the Xbox, and IBM knew that they would be coming to them soon for a new CPU based on newer technologies but without the unnecessary components that a computer cpu would need. It could of happened either way, but I doubt Nintendo would customize the cpu much at all.
Yeah, I know that it's a 1ghz gpu at stock, lowering it by 10% to 900mhz would give you lower TDP (which is all that really matters when we talk about console limits)
You could in fact remove ram power from the GPU's power draw, because you'd count the ram separately from the GPU as it will likely share a bus with the CPU, The point you are trying to make about AMD making a GPU from scratch doesn't make sense, that wasn't how the 360's gpu was created, and I doubt it will be how Wii U's GPU will be created, I mean your order is sort of tall for the current Nintendo, sure they will customize the chip, get certain features that they want, and cut out others, in the end it might not look like a HD7700 series, or even an HD6700 series, but it will likely start from one of those two.
40nm or 28nm makes the most sense for a GPU, over time the 28nm would of course be cheaper, and TSMC would have the capacity to fill far more orders as the year progresses, Wii U would be big business for them, and should be something they would be very interested in in the long run. Also even if you do get better yields at 40nm, you make more 28nm per process, so it's really hard to say which is better IMO, especially in 6 months. For Nintendo, with wattage, performance, and space for their architecture, I think 28nm is a no brainier, but I am not a TSMC customer, so maybe it does look grimmer than I've laid out.
The main problem i see with a 32nm chip, is you are designing a brand new chip, on a architecture AMD has never designed a GPU for, at least nothing like this, it would make much more sense to go with an existing design, that would of existed in some form even 2 years ago, when Nintendo would of been figuring out what they wanted.
In the end, this really doesn't matter, it will be powerful, and it will fit in the box without catching fire, and I trust Nintendo won't have any RROD issues either, thanks for arguing your points, I see where you are coming from, but I just am not sure I buy it, feel free to reply, I'll read it tonight when I get to work and reply when I can.