Wii´s CPU clockspeed around 1GHz

I have read a lot about Wii´s specs and I think you too. The most realistic specs have come from Matt of IGN in interviews he has done to trust developers. In one interview the developer told him that the estimated Wii´s CPU clockspeed was around 729Mhz (conclusion made primarly from CPU testing benchmarks and also from Nintendo documentation). This interview was made some months ago before E3. Also 3th party developers told to Matt that they will receive final develpment kits in june (after E3).

In E3 we saw that many if not all the Wii games were running on unfinished Wii hardware, hardware that had a Gamecube case. Many of the games seem to be just upgrades of Gamecube´s ones graphically speaking. Nintendo itself has said that the hardware is not final, and it could change before launch. I really think that Nintendo intensionally made the first develpment kits with slower specs so developers could play around with the new interface rather than pushing poly counts. In E3 Nintendo had to show that the interface was working good and that is not just a gimmick idea.

With this information we really don´t know for certain how fast Wii´s CPU clockspeed will be in the final hardware. But we know Perrin Kaplan said some time ago that Wii will have 2 to 3 times the power of a Gamecube. We also know that Nintendo is the most conservative console manufacturer when talking about specs and if Nintendo talks about horsepower tryies to talk about realistic numbers. Gamecube numbers where focus around realistic in game numbers and not peak ones. So this statement from Perrin Kaplan could be real.

We know Gamecube´s CPU was made by IBM. This CPU has the following specs (Nintendo published this specs around Gamecube launch):

MPU ("Microprocessor Unit")* : Custom IBM Power PC "Gekko"
Manufacturing process : 0.18 micron IBM copper wire technology
Clock frequency : 485 MHz
CPU capacity : 1125 Dmips (Dhrystone 2.1)
Internal data precision : 32-bit Integer & 64-bit floating-point
External bus : 1.3GB/second peak bandwidth (32-bit address space, 64-bit data bus 162 MHz clock)
Internal cache L1: instruction 32KB, data 32KB (8 way) L2: 256KB (2 way)

Nintendo said that this is a custom chip designed for the Gamecube. But as we will see this chip is not greatly customized. Look the green box in the image:



The 750CXr is very similar to the Gamecube´s Gekko CPU in a 90%. Customization means a more expensive technology. So to mantain an affordable console, Nintendo chose an existing PowerPC and made small changes to it to make it situable for a videogames system.

I think Wii has a similar philosophy behind. Use an existing PowerPC and made twicks to it, but esencially the chip will be an existing one on the market.

So I think the information about how many times Wii is more powerfull than Gamecube could help us find which CPU Wii uses, cause is a statement from a Nintendo source. So 2 to 3 times could be thought as 2.5 times, right? Let keep it low, so we have Wii having 2x the power of a gamecube.

So based in the CPU numbers on the image we can tell that the most realistic number that describe us the power of the CPU is the Dhrystone MIPS. Why? cause is a performance measurement. This quantity represents the realistic number of instructions the CPU crunches in a second. The Gekko has around 1125 MIPS. 2 times this number is 2250.

In the same image (the blue box) we have a CPU that is near this number. It is the 750GX with 2320 MIPS. This MIPS number comes from a 1GHz 750GX. If we use the 2.5 factor we have 2812.5 MIPS. So a 1GHz 750GX with 2320 MIPS is lower this 2812.5 MIPS number. There are faster CPUs but they have MIPS numbers considerably greater than the 2812.5 MIPS mark (Around 5000 MIPS).

This table of specific chips are the ones that IBM launched to the computer market (well known to be the heart of many Mac computers). Maybe Gamecube´s CPU or Wii´s CPU are not a GX, CXr or other, but they are based on these chips. So counting the statement from a Nintendo source about the Wii compared to the Gamecube powerwise and from realiable information from IBM we can say that the Wii´s CPU clockspeed is around 1GHz in the pesimistic case. Which chip? I don´t know but It will probably be based on one of these chips, maybe the 750GX.

There is official info from Nintendo that tell us the following:

CPU: PowerPC CPU (code-named "Broadway"). Made with a 90 nm SOI CMOS process, jointly developed with and manufactured by IBM.

The 750GX is made with a 130 nm SOI CMOS process and the official information tells that is a 90 nm process. This difference could be because some processors can be shrunk through the time, so the SOI CMOS process changes to a smaller one.

http://www-3.ibm.com/chips/...