Monday, December 3, 2012

Breaking the Wii U down; what each bit means


Want to know what the difference in a GPU and a GPGPU actually is? We’ve got just the information you need to gain a better understanding of what makes the Wii U tick, and bring it to you in such a way that makes it simple to understand by all.

 In our recent article, Is the Wii U Powerful enough?, we took a deep look into the rumours surround the Wii U’s supposedly “slow” processor and found out that the idea of the Wii U being a true “next generation” console from a power standpoint was loosely based on it having a tri-core IBM POWER7-based architecture, which it didn’t ship out with. We also explored the insight of a few respectable developers and based on the information we had acquired at the time, we came to the conclusion that the Wii U was likely to be on-par, to a little below the specifications of current generation consoles, but even today we still don’t have conclusive evidence to make an official claim to this.

Today, the arguments are still on-going and while for the majority of those enjoying their time with their shiny new Wii U units (we’re having a blast with ours) most likely could care less, we’re back again to discuss a new rumour and most importantly to give you the knowledge and understanding of what’s inside the Wii U and how these parts actually work – once you understand how it works, you’ll realise just how powerful it could actually be.


Another Rumour

CVG ran a surprising article yesterday and the first two lines were the most important bits, which I’ll duplicate in their entirety for you to read:

"A well-known hardware hacker has published what is believed to be the processor and graphics card specs of Wii U."
"It is said that the Wii U processor carries a clock speed of 1.24 GHz - less than half the speed of the PS3 and Xbox 360. However, its GPU core is believed to run at 550 MHz, which is the same speed as Sony's home console and a tad faster than Microsoft's."

Let’s get this over with really quickly, there’s been a lot of talk back and forth about if the processing speed reported here was an idle speed, which means this number means absolutely nothing if so and is just more talk for the media’s attention. I’m also not going to debate this issue here today, as there’s simply not enough substantial evidence to even try to formulate an opinion on here. What I am going to do, is show you how the Wii U actually processes information and that will in turn show you how far off base this rumour is – there are entirely too many things that aren’t factored into the equation here.

Let’s look back at CVG’s piece though. In the latter lines they speak of Wii U’s supposed clock speeds for the CPU, but then immediately drop a comparison to how the Wii U’s GPU stands against it current competition. While I trust that the author at CVG understands that there’s a difference in a CPU and a GPU, the vast amount of comments I’ve personally read around the internet and social media sites clearly show that the majority of ‘gamers’ don’t know the difference. It’s understandable too, seeing how console gamers enjoy not having to worry about upgrading their consoles’ hardware (e.g. graphics card, etc.) to keep up with new game releases, but with the current arguments about the hardware inside of the Wii U trending within the industry, I’ve noticed that these same people are the least equipped of them all. So here today, let’s leave the arguments on the side-line and gain a better understanding of how the Wii U actually works – shall we?


The CPU

Wii U's CPU is the smaller component on the left
The CPU, or “Central Processing Unit,” is the brain of the console. The CPU executes and handles of the arithmetical and logical calculations stored within it. What you really need to know here is that every CPU has an internal clock within it and this clock regulates how many cycles (also known as “ticks”) the CPU needs to execute each new instruction. In short, the faster the clock speeds, the more information the CPU can handle within one seconds time.

Just for a little more background here, you oftentimes hear people talk about the “complexity” of the CPU – what does that mean though? This refers to the how many transistors are embedded into the microprocessor. A transistor is the very start of where information flows. When powered they form a “1” and when deactivated they produce a “0”: binary language. These transistors can activate thousands of times per second and how many are embedded into CPU is the fundamental basis on how fast the CPU ticks. When you take into consideration that there are hundreds of millions of these tiny transistors embedded into each CPU, you’ll understand why it’s considered to be “complex.” This is also where the generational gap comes from too, seeing how the transistor count typically doubles within a year’s time.

According to Wikipedia (who’s been doing an awesome job staying up-to-date with this information), the Wii U features an “IBM PowerPC 750-based tri-core processor.”

What’s a “tri-core processor?” This is where three separate CPU units, or “cores”, are linked together to form one multi-purpose CPU unit. Where a single core processor has to do everything on its own, a tri-core processor would in turn break these exact same instructions apart for three separate processors to work through – greatly improving the speed of the job being completed. If it were humans doing the work, if one man can complete the job in eight hours alone, two men working together can complete the job in four hours’ time, etc. Simple, isn’t it? While the clock speed of each individual core stays the same, the speed of the information being computed is greatly increased as a whole. On paper, the clock-speed of the tri-core unit isn’t the speed of one core, but the speed of how fast the information is computed through all three cores.


The GPU

Wii U's GPU
The GPU, or “Graphics Processing Unit,” is a very efficient unit that’s used for computing images, especially three-dimensional. See, graphics rendering is overly taxing on a CPU and a separate GPU unit helps to alleviate the CPU being pulled down from the constant strain of producing the visuals, which is why they’re commonly found in videogame consoles. But a typical GPU has strict limitations as to what it can be utilized for.

On the other hand, a GPGPU, which is what is what is found within the Wii U, is a “General Purpose Graphics Processing Unit,” which means that some of  the these limitations to only compute graphics are removed and it can in turn help out with the normal function of the CPU as well. In easier terms, if a Wii U title is pushing the CPU to its limits and creating issues within the game, a slight drop in visuals would free up the GPGPU to supply a boost to the CPU for stability. Also, developers could scale down their games’ graphics and use the GPGPU’s additional power to bring better physics and features to their games that wouldn’t be possible on the CPU’s power alone. While the inner workings of the GPGPU is overly complex (going far beyond my basic knowledge on the subject), I do know this – the addition of a GPGPU for Wii U does add a significant amount of complexity to its architecture and it’s one that will likely be a focal point that developers take full advantage of in the future to push Wii U to its maximum performance levels.

Wii U features a custom AMD 7 Radeon High Definition GPU with a “significant” amount of DRAM embedded into the die. As I mentioned in my earlier piece, this is a great piece of tech and one that looks to doubles that of what’s found inside the Sony and Microsoft’s current consoles.


RAM

Memory Chips (RAM) found within the Wii U
This is a big confusion point that I’ve seen regarding the Wii U’s specifications – by itself RAM does not create “next-generation” consoles. RAM, or “Random Access Memory” is where the data is stored and manipulated via the same type of transistors found inside the microprocessor (in binary code). RAM comes in the form of a “Memory Chip.” On each memory chip, there are millions of tiny transistors and capacitors, where the transistor fires the code to be stored ( “1” or “0”) and the capacitor stores it for future accessibility.

If a CPU has little memory available, it has to output the memory stored during its computing process forever to allocate enough memory for its next calculations to be made. So if there’s not enough memory and a certain calculation has to be constantly reprocessed, instead of just accessed from storage, the overall speed of the CPU will be slower. To put it in the simplest of terms to understand, the greater the amount of RAM that’s available, the better chances you have of allowing your CPU run at full capacity.  

This brings us to DRAM, which is “Dynamic Random Access Memory.” This is volatile memory. In short, this means that it forgets what’s stored within it very frequently. This is the primary type of RAM used in gaming consoles, because of its simplicity: one transistor to one capacitor. As I just mentioned, the downside to DRAM is that the capacitors leak their charge and need their charge to be constantly refreshed, but this easily remedied via specialized on-board circuitry.

But, how does DRAM make things better (faster)? That’s actually quite simple: cache memory. Because of its simple complexity, it’s a perfect memory type to store cache memory upon. Cache memory is very small, extremely accessible random access memory that much faster to access than the larger memory banks stored in typical RAM. Cache data is data that’s frequently used, so when the CPU needs it, it goes to cache memory to search for it first and if it isn’t there, then it goes into the banks of memory stored in RAM searching for it, which takes additional time – DRAM improves the clock speed of the CPU!

Wii U packs 2GB of RAM, with one GB allocated specifically for playing games. The other GB of RAM will likely be used for system operations, etc.


eDRAM

While eDRAM should probably be in the above section under “RAM,” I’m separating it here for a reason – this is a big confusion spot for many people who are trying to figure out all of the Wii U’s specifications.

Firstly, much like the GPU vs. GPGPU confusion, eDRAM is not an entirely separate entity either. Instead, eDRAM is actually, “embedded Dynamic Random Access Memory.” This means that the DRAM is just that, embedded into the microprocessor of the CPU itself – for Wii U, the eDRAM is found within the GPU. This is a cool trick that brings along big advantages for the processor: larger buses and faster operating speeds. Buses are the ‘highways’ of the computer, where information flows from one component to the next; the wider the lanes (buses) are determines the amount of information that can travel down them at once. The faster the information flows, the faster the computing process is, which means the overall clock speed of the CPU are once again increased.

This is why the amount of eDRAM is another major factor at play with the Wii U’s maximum processing speed and capacity. We know there’s a “significant” amount of eDRAM found within the GPU, but we don’t know the full extent of what’s embedded within it – the more the better. This becomes exponentially more important when you factor in that the Wii U utilizes a MCM, which is next up to cover – make sure to refresh your capacitors to ensure that you can compute what I’ve only just told you, it’s another vital factor for finding Wii U’s true processing capacity.


MCM

Here you can see the MCM
Multi-Chip Module, this is another factor that’s isn’t talked about very much around the Internet, but it’s another bit of trickery that’s found within Wii U and one that like the many other, is another way to squeeze more power out of the CPU. A multi-chip module is where multiple components are placed onto the same die, or square on the circuit board – allowing the multiple components to efficiently work together in unison.

For the Wii U, the multi-chip module setup finds the CPU and the GPU both placed together on the same die, allowing them to work together at the highest efficiency possible – another clever trick Nintendo’s used to maximise CPU performance, especially when you consider that the GPU and its unknown amount of eDRAM can attribute to the CPU, because of its general purposing abilities (GPGPU).

Here you can see the massive Heat Sink 
But there is a downside to putting all of this onto a single die and this comes in the form of heat. A tri-core processor and a GPU already create a substantial amount of heat on their own, but placing all of this together means that all of this heat is being created within a very small area. This is why the Wii U includes a very large heat sink, as well as an oversized fan within it. If you’re unfamiliar with a heat sink, it’s an aluminium alloy component that not only redirects heat, but it can also dissipates some of it as well.

For any of you reading this that have ever experienced the dreaded Red Ring of Death (RROD) on Microsoft’s earlier Xbox 360 consoles, you know exactly what the end result of heat can do to a system. At a lesser extreme though, overheating can also slow the processors’ speeds. If you’re tried playing a high-end PC title on an average system and pushed its performance to its maximum for an extended period of time, you’ve likely experienced these negative effects first-hand before. The longer you play and the hotter the system gets (if not efficiently cooled), the further the overall gameplay experience continues to falls apart.

On a brighter note, Nintendo is known for developing consoles that are relatively free of issues and I’ve no doubt that they exhumed all of the problems that utilizing a MCM configuration within the Wii U could produce. Still, I would make certain that your Wii U console is placed in an area with adequate ventilation – don’t cram it into a small entertainment centre! This is also why this a top priority in the Quick Start Guide that comes with the Wii U and you should most definitely abide by these instructions to the fullest of their extent.

But, I’d be remiss for not bringing forth the question that’s in my head right now into fruition within this article – will we see Wii U owners ignoring these warnings, cramming their Wii U units into an unventilated space and find them with a system failure from overheating? I’d think it’s entirely possible, but I’d like to think that it’s likely not going to be seen until developers start making use of the advantages of the MCM – greatly increasing the heat produced throughout extended gameplay sessions.


The Breakdown

Now that we know what the major parts that make the Wii U tick and know how these parts actually work – what does all of this mean for the Wii U in general?

For starters and most importantly, it means that the Wii U is expertly designed to make a somewhat unimpressive CPU (individual cores) run at impressive speeds. Utilizing tri-core architecture greatly increases the overall clock speed of the CPU already, but placing the GPGPU and its “substantial” amount of eDRAM (which can both boost the clock speeds of the CPU) on a multi-chip module increases their combined efficiency even greater. This also means that the Wii U’s architecture holds numerous ways to maximise its performance when put into the right developers’ hands. It’s likely we’ll see jaw dropping HD titles that run in native 1080p, taking full advantage of the GPU (and it’s eDRAM), but offers a gameplay experience that’s less taxing on the CPU – think thatgamecompany’s Journey on Sony’s PS3.

We could also see games like Gran Theft Auto 5 come to Wii U without issue, if the developer scales down the graphics to 720p and takes full advantage of the numerous ways to boost the CPU’s performance to handle the burden of running a constantly moving open world environment. Of course, these are my personal speculations, but when broken down into this perspective, I’d like to think that we haven’t even begun to see the true potential of what the Wii U can produce – making the recent rumour I brought up earlier seem somewhat irrelevant- doesn’t it?  

Was the speed found in the recent rumour that of a single core of the Wii U’s CPU alone? Was the GPGPU factored into the equation when checking the CPU’s clock speed? Were the advantages of the MCM utilized when that speed was clocked? Do you now see how vital all of this is to finding out how powerful Wii U truly is? I hope so.

The last point I’d like to touch on briefly, is that there’s a reason that Nintendo has opted for all of this: cost. Developing a home console with a tablet-like controller is already expensive, but having to build a powerful HD console that can stream the information to it from afar makes that cost even greater. Nintendo could have easily slapped quad-core POWER7-based architecture into it and had themselves a true “next generation” console, but that would’ve come with a much higher cost to the consumer – that’s not the Nintendo way of doing things.

Instead, their engineers have cleverly crafted a powerful console from somewhat outdated technology (one that I believe will be shown to be more powerful than current generation consoles in the coming months) that offers up a near overabundance of control options and allows developers to run wild with their creative minds upon. When the President of Nintendo in North America, Reggie Fils-Aime, stated that Wii U is a “new generation” of home consoles, I think he was right on the money. The abundance of ways to play games on Wii U sets it apart from other dedicated gaming consoles and as you can now see, there’s plenty of options to get additional horsepower out of Wii U if and when it’s needed – now it’s up to the developers to make the best of these hardware options that have been placed before them.

As I bring this piece to a close, I hope that I leave you with a better understanding of how these components that are vital to powering the Wii U (and other computers) actually work and that you see that sometimes (like I said in my last piece) you’ve just got to dig a little bit deeper to find the ‘truths’ behind the matters at hand. In the coming months, we will eventually know what Wii U’s maximum performance level actually is and it’s quite likely that by that time comes, most everyone will be focused on other things within the industry. Here at Digitally Downloaded, we share a common mentality among us and that’s to “have fun playing games, no matter what you’re playing them on.” If there’s one thing I’m absolutely certain of, it’s that there will be a lot of fun to be had with a Wii U GamePad in hand. 

Now that you have this information – does this change your mind about the recent rumours surrounding the Wii U's power, or lack thereof? We’d love to know your thoughts in the comments section below. 
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