http://www.insidegam...-gpu-is-sterker
well I can't say how reliable this site is but they say they got that information from a member of Asscreed team from ubisoft.
According to the article it refers to this GameSpot interview, google translate says ubisoft "stretched" this information, the actual translation means provided.
So what it's saying is that during this interview they say the Wii U is slightly powerful against the other consoles.
Which is wrong, what they said was its great to be able to have this game on PC, PS3,360 and Wii U and that it's a evened out playing field now.
That sentence was mis interperated by that news site, as they assumed they meant it's near equal in power.
Well that's that rumour debunked. On to the system, size of the system does matter, graphics cards get hot, very hot and it's required to have adequate cooling. The Wii U is almost Wii size, so it questions if the Wii U gets that hot or not. If it doesn't why? It could be a GPU that doesn't get that hot which would imply a lower end GPU.
Though it could be a GPU that is customised to run less hot. Thought I know a few X770 Radeon cards that ran fine with passive cooling.
I am still certain that the GPU has to be a 6 or higher series, doesn't make sense for Nintendo to call it an AMD Radeon based GPU.