The edram will not be used for the CPU, it will be used for the GPU. Beyond 2-3MB of cache is a waste for a gaming CPU, it's the GPU that will make the most use of the edram.
Also you seem to be confused by 300mm wafer. 300mm plant means that the wafer is 300mm in diameter, not that it produces chips that are around 300mm squared in size. The Wii U CPU will not anywhere near 281mm2. With the edram and GPU it might come to that.
300mm wafers are a large wafer. The largest. If you dont want yield issues when manufacturing large chips, you use the big wafer, not the 2-inch 4 inch 6 inch or 8 inch. Bigger wafer=more chips after sli e and dice. Something absolutely imperitive the larger the chip. Its why watson power 7 packages were manufactured at the same plant.
simply dividing the chip size By 2 is obviously NOT the final answer in reducing the size of this product, if you are knowledgable enough to know this i suspect you already know whats to be said next but were being purposefully obtuse.
after removing unnecessary memory controllers (quite large on the p7 running the entire height of the chip and a good little width) server bound i/o's, unnecessary edram and other components not necessary for a something thats not a super.computer or a server, the chip would be considerably smaller than what i stated by simply splitting it in half for 4 cores. Likely around 200mm squared.
Power 7 L1 & L2 cache sizes have been reduced, from power 6 not enlargened.
L3 caches have historically been external, with the sole exception of power 7, so i highly doubt you were referring to that.
Its not the SIZE of the cache that makes power 7's edram special, everyone gets distracted by the on die l3. Yeah, its cool having a whopping 32MB on die, but its not the only star of the edram show.
p7 L1 cache=32 KB.
p7 L2 cache=256 KB.
p7's l1 and l2 caches also feature special new edram technology.
You are asking what so much ram bandwidth can do for a cpu? (an agressively out of order cpu that need only wait on ram to scheduele any damn thing it wants to be crunched?)
Power 7 only has 1.2 billion transistors. Yeah, I know, 'only', the point is, commercially available computers, crud you buy from best buy with gateway logos on it has intel i7's in it with 2.1 billion transistors.
So why does power 7 stomp i7 when it appears to be at such a disadvantadge?
Because its not your run of the mill edram. Each edram cell has the functionality of a six transistor static ram (6tsram) cell.
power 7 has the equivilant functionality of a 2.7 billion transistor processor. Requiring less than half the transistors to actually power. Less than half the transistors that generate heat.
People dont understand how flexible a chip ibm made. This thing performs spectacularly per thread per.core.per watt.
Anyways, Nintendo is NOT looking for a fast cpu. its p7 based cpu wont be slinging flops and simd loops at break neck pace. Videogames were NOT the sole reason Nintendo chose this processor.
Speed is not the sole kind of power when it comes to.processors, its flashy, its exciting, and its damn near tangible in the gaming industry... But its not the only thing.
People expecting speed are looking at tue power problem from the wrong perspective. Its like they want 9 women to have a baby in one month, and when they see its not possible they say see, it cant be done, that cant be what it is.
well, no, 9 women cant have a baby in one month, but 9 womem can have 9 babies in 9 months.
Can you think of any large, intrusive, ambitious software technologies nintendo announced that would be independantly doing all kinds of stuff the cpu would need to track while the player plays his game?
Edited by 3Dude, 27 September 2012 - 05:03 AM.
