After looking at the CPU in wsippel's post, I wanted to look at the GPU this time when I had free time. It was mentioned to him that the GPU was running at 500Mhz. Adding that with the scraps of info we had we seem to be able to conclude that it sounds comparable to an underclocked 4830. This is due to the 4830 being normally clocked at 575Mhz and uses GDDR3 (the rumor had the GPU clocked at 500Mhz and using GDDR3). What I did was "dust off" some old benchmarks for this processor and looked at other info on the GPU. Obviously we can't make a 1:1 comparison of a PC to console especially with customizations for the console version vs the stock version for PC. The idea wasn't to look directly at the 4830's power, but to compare it to others in that range to try and get an idea of why Nintendo would possibly target that GPU as a foundation. I'm not justifying the usage as I'd like to see them go with a little more power as a "base", but attempting to understand Nintendo's thought process that would lead to this GPU choice hypothetically speaking.
First thing I see them maybe using it is the cost. At its release the 4830 was highly praised for its cost versus performance.
Second would be it's TDP. According to
Wikipedia's comparison chart out of the four RV770s it is clearly the lowest of the four. (All chips 55nm)
4730 (GDDR5) - 110 W
4830 (GDDR3/4) - 95 W
4850 (GDDR3/4) - 110 W
4870 (GDDR5) - 150 W
Third is actual performance. When looking at the performance and taking the first two into consideration I can see why Nintendo would go this route. The difference in power versus cost and temp may not be that justifiable. Here are some of the benchmark tests I looked at. The card itself has 512MB of GDDR3 in these tests. Also a lot were redundant so I narrowed it down to just a few.
The first one I would consider "not so realistic" because of the amount of memory used.
Uses an Intel Core 2 Extreme QX965 and 4GB of memory
This one focuses on the 4830, but also uses the 4850 in the comparison. What I liked about this one is that it also provides temp and power usage. To avoid clicking through every page, you can use the Table of Contents drop box on the right.
The next two are "more realistic" because they use 2GB of memory.
http://www.guru3d.com/article/radeon-hd-4830-review-his-technology/
This one similar to the one above.
http://www.techpowerup.com/reviews/Sapphire/HD_4730/
This one is centered around the 4730, but it provides a lot of different cards for comparison.
What stuck out to me while doing this is that the 4770 (RV740, 40nm, GDDR5) has an advantage in performance and power (TDP 80 W), but I assume the cost will not justify its usage when also considering the customized version of the 4830 could be made on a 40nm fab reducing TDP.
When looking at the 4830 versus the others in the group, I can see the usage of a decent amount of eDRAM (for the GPU, not CPU and mentioned in the rumor) making up a lot of the difference, if not helping it pass the others. This of course does not include other customizations.
Speaking of which, we know that the Xenos would be considered an R500 that implemented unified shader architecture that was eventually used in the R600 line. It also used DX9 that took elements from DX10. It's very reasonable to believe Wii U's GPU will do the same.
First looking at the API, we had reports about DX10.1. That is irrelevant because we know that Nintendo will not use DX, but instead OpenGL. IMO the pointing out of DX10.1 was just referring to the level of card being used. Something to point out dealing with OpenGL is what can be done with it. I got this link from a poster on IGN a little while back and there is a very interesting part in this blog article.
http://blog.wolfire.com/2010/01/Why-you-should-use-OpenGL-and-not-DirectX
1. OpenGL is more powerful than DirectX
It's common knowledge that OpenGL has faster draw calls than DirectX (see NVIDIA presentations like this one if you don't want to take my word for it), and it has first access to new GPU features via vendor extensions. OpenGL gives you direct access to all new graphics features on all platforms, while DirectX only provides occasional snapshots of them on their newest versions of Windows. The tesselation technology that Microsoft is heavily promoting for DirectX 11 has been an OpenGL extension for three years. It has even been possible for years before that, using fast instancing and vertex-texture-fetch. I don't know what new technologies will be exposed in the next couple years, I know they will be available first in OpenGL.
Microsoft has worked hard on DirectX 10 and 11, and they're now about as fast as OpenGL, and support almost as many features. However, there's one big problem: they don't work on Windows XP! Half of PC gamers still use XP, so using DirectX 10 or 11 is not really a viable option. If you really care about having the best possible graphics, and delivering them to as many gamers as possible, there's no choice but OpenGL.
This section provides a link to a .pdf that says showed the extension was originally for
OpenGL 2.1. That makes it sound to me that if the GPU can use OpenGL 4.1 that would be "icing on the cake" so to speak. So we can believe at least a part of hanging with DX11-level cards is in place.
The other side is hardware. Wondering if the GPU borrows from the higher-level series of AMD GPUs is more tricky because of the lack of information. But while I was in Detective-GAF mode on the other stuff I noticed this. First we know that the Wii U uses HDMI (version not verified). Next we know that the disc is "blu-ray equivalent" and Iwata semi-confirmed Wii U can support 3D playback. This would leave me to believe that at worst Wii U uses HDMI 1.3a. Why is this important? This comes from the
Wikipedia multimedia section on the R800.
One major milestone is that the Evergreen GPU family supports HDMI 1.3a output. The previous generation R700 family GPUs only support up to LPCM 7.1 audio and no bitstream output support for Dolby TrueHD and DTS-HD Master Audio audio formats to external decoders. This feature is now supported on Evergreen family GPUs.
This would lead me to believe there maybe indication that the R700 GPU is borrowing components from the a higher-level series. If true then I wonder what else could be borrowed? Tessellation unit anyone?
So we'll see what happens as for all we know they'll be using something a little more powerful for a foundation. But this is my guesstimation based on what little we know so far.
