There's a lot of rumor and speculation going on about the next gen consoles from Sony and Microsoft.  I decided to take a thorough look at these rumors and see if I can put them together to create some logical guesses about what we can expect in the next year or so.

I'll be focusing mostly on graphics power, as I'm not very familiar with the differences between IBM and x86 CPUs.  I'll also be referring to the GPUs floating point operations per second (FLOPS) when comparing how powerful they are; it might not be the best metric for determining a graphics cards prowess, but it will work for the sake of this post.
Leaked Sony Development Kits: Codename Orbis
According to IGN, the first Sony PS4 dev kit,  was packing an "A8-3850 quad-core 2.9GHz processor with an integrated graphics chip (6650D). The APU will work in tandem with the system's dedicated GPU, the HD 7670, a DirectX 11-enabled card clocked to 1GHz with up to 1GB of dedicated VRAM" and that Sony will implement an asymmetrical crossfire (dual gpu) configuration that will work to split graphics load between the two GPUs.  When these specs were first released, many people called them underpowered, but it's actually quite a bit more powerful then the PS3.  How much more powerful?  Well the PS3's gpu is capable of 228.8gflops, meanwhile, the PS4 Dev kit sits around 1248 gflops (6650D = 480gflops, 7670 = 768 gflops), making it capable of 5.45 times more floating point operations per second then the PS3, not a bad leap if you ask me.
Information regarding the second PS4 dev kit, suggests that Sony has moved to an A10, from an A8.  This means a slightly faster quad core CPU, and a boost to the onboard graphics to the 7660D.  It also mentions the system will have 8 or 16gb or RAM.  This report doesn't mention a second, discrete, graphics card; but I believe that Sony will still be putting one into the system.  And I'd be willing to be it will be more powerful than the HD7670.  This report also suggests that this is the 2nd of 4 dev kits that Sony has planned, with the next one coming in January.  This 2nd leaked dev kit, assuming at minimum the HD7670 as the discrete GPU, is capable of 6.04 more FLOPS then the PS3 (1382+ vs 228.8)
Microsoft's leaked dev kits, codename Durango
There have been a few leaks regarding the next gen xbox's hardware.  Initially it was thought to be IBM CPU, with an AMD GPU, and that MS was going for a SoC (system on chip) design right off the bat.  Most newer rumors point to an AMD CPU and GPU.
It was very interesting when a supposed developer posted pictures of the durango dev kit, and even tried selling it on ebay.  That individual claimed that MS was using an Intel CPU and an nVidia GPU, which contradicted every other rumor out there.  Well, another rumor from VR-Zone, sugests that the initial dev kit with Intel and nVidia hardware was real, and was a very early build so developers could get an estimation of the power of what the 720 would be like.  It is said that it contained an 8 core Intel Sandy Bridge processor (though it's likely they mean 4 physical cores, and 4 logical cores) with an nVidia GTX 570.  And now current hardware is using and 8 core AMD CPU and GCN based (HD 7xxx) GPU.
How does the initial version of durango compare to a 360?  Nvidia's GTX 570 puts out 1405gflops, while the Xenos GPU in the 360 musters 240gflops.  Making the first dev kit 5.85 times more powerful then the 360.
What is 4K, and what does it mean for the next gen?
4K is a video resolution of 4096x2160, it has slightly more then 4 times the resolution of 1080p, which it's set to replace.  The most recent leak of the Sony PS4 dev kit suggested that Sony was targeting 4K at 30fps, or 1080p at 60fps in 3D.  Well, 4K/30 and 1080p/60 (3D) would require just about the same amount of processing power: 1080p/60 (3D) = 248832000 pixels per second; 4K (4096x2160)/30 = 265420800 pixels per second.
On current hardare, the majority of games run at 720p/30, while some run at 60fps (I should also note that 720p/60 is essentially equal to 1080p/30).
Calculating pixels per second equals: 720p/30 = 27648000 pixels per second, 720p/60 = 55296000 pixels per second, 1080p/30 = 62208000 pixels per second
Taking those numbers and comparing them what was is needed for 4k and we get: 4k vs 720p/30 = 9.6 times more pixels, 4k vs 720p/60 = 4.8 times more pixels.  So, in order for next gen systems to do 4K at 30fps or 1080p/60 in 3D, they'll need to put out almost 5 to 10 times more pixels per second then they currently do.

Epic games, Unreal Engine, and more

In 2011, Epic unveiled their Samaritan demo, it used dx11, and was meant to show what Epic was hopping the next generation of console games would look like. Much of the tech from this demo will go into Unreal Engine 4, which is expected to be a dominate game engine next generation, just as Unreal Engine 3 has dominated this gen.  At the D.I.C.E. summit this year, Epic's Tim Sweeney said that a console would require 2.5 tflops of computation power, 10 times more then current consoles.  I believe that Sweeney's statement is more then just that of fact, but is a guideline for the kind of power we can expect from Sony and MS.
Epic games has a lot of pull in the industry, when they were developing Gears of War for the xbox 360, which is the first game to use Unreal Engine 3, they were able to convince MS to increase the system RAM from 256mb to 512mb.  A move which is said to have cost MS around $1 billion.  I think that when the PS4 and 720 are officially unveiled that will have at or near to 2.5tflops of graphics power.
Square Enix worldwide technology director Julien Merceron, recently teased that the company's Agni's Philosophy demo would be shown again in June, on "different platforms then before" and that it "won't run on a PC"  Hmm, I wonder what he could mean...
My predictions:
I think when the final designs of the new systems come out, they will look something like this:
Xbox 720:  AMD 8 core FX 8150/8350 cpu, 8 gigs of RAM, and a graphics card somewhere between the HD 7870 and 7950, which puts it at 2.56 and 2.87tflops respectively.
PS4:  AMD 4 core A10 APU (CPU + GPU), 8 gigs of RAM, and a discrete graphics card somewhere around the HD 6870 and HD 6950, which would make for a combined output of 2.61 and 2.86tflops respectively. 
The graphics architecture of the AMD HD 6000 series is based on VLIW4, whereas HD 7000 is based on the newer GCN architecture.  There are some rumors that point to Sony using a GCN based card as it's discrete card, but I feel like it would be a more cohesive, developer friendly, design if both cards used the same architecture (the GPU in the A10 chip is VLIW based), but then again, I'm not smart enough to know if that really even matters.
From my point of view the two consoles are looking pretty even overall.  With Sony using 2 small, less expensive GPUs.  And MS using a larger more expensive part.  Some might say that the Xbox's 8 core cpu is going to give it an advantage over Sony, who will likely only be using 4.  The thing is, Microsoft will have Kinect 2, which could very well chew up several cpu cores.  There are also several rumors about augmented reality, body sensors, and DVR capabilities, which could use even more cores.  Xbox 720 might need the extra 4 cores just to stay even, with all the additional things it might be doing.
In the end, it's looking like we can expect to see next gen consoles from Sony and Microsoft that are 6-10x more powerful then current generations.  Not only will they be more powerful in terms of raw power, but they'll be based on DX11 hardware, which will bring a whole new set of eye appealing visual techniques and dynamic effects.
My wallet is telling me that I'm not ready start spending money on new consoles, but I can't help being excited for what the future holds in gaming.

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