Background Information:
-In today's day and age the GPU is the bottleneck LONG before the CPU. Thus the GPU will be at the center of what is compared.
-Both consoles use the same AMD 7000 series architecture so they can be directly compared to their desktop equivalent.
-I have exstensive experience overclocking and using many of the cards from the 7000 series.
-In my expereince, the 7000 series benifits directly from changes in Core/VRAM speed. This sounds obvious but what I mean is when I overclock my 7970, its in-game performance boost is equal to ((OverclockedCore/OriginalCore)+(OverclockedVRAM/OriginalVRAM))/2.
-Theoretical computational power does not translate directly into gaming performance. For instance a 7970 is FAR more powerful computationally than the 680, but it is only a little stronger.
-Latency in memory is no where near as important as speed when it comes to grachics cards.
-The most important specs are CoreClock, VRAMClock, bandwidth, and # of compute units. That is what I will analyze here.
-The HD 7870 is roughly twice as strong in game performance than the HD 7770.
Comparing Xbox One to the HD 7770
The 7770 has:
-10 Compute Units
-1000MHZ Core
-4500 GHz VRAM
-128-bit Bandwidth
The Xbox One has;
-12 CU
-800MHz Core
-2133MHz VRAM
-256-Bit
So first off the Xbox One has 20% less core speed while the 7770 has 20% less cores; thus they cancel each other out. The Xbox One has double the bandwidth so its VRAM should be effectively 4166MHz compared to the 7770's 4500MHz. The ESRAM and the small tweaks to the One's architecture should make up the rest of VRAM difference. Thus as you can see they very easily compare to each other and it is more than fair to say the One effectively has a 7770 in it.
Comparing the PS4 to the 7870:
The HD 7870 has:
-20 CU
-1000MHz Core
-4800MHz VRAM
-256-bit
The PS4 has:
-18 CU
-800MHz Core
-5500MHz VRAM
-256-Bit
So the PS4 seems 10% stronger in the CU department and 20% weaker in the core speed area. But the VRAM in the 7870 is 15% slower. So we are left with a 15% difficency that will easily be made up by the PS4 GPU's HSA improvements to round it off to a 7870.
Other things to factor into the overall performance difference:
So at the end of the day these are the facts. I laid them out step-by-step. People who say the PS4 may run at 60FPS while One runs at 30FPS with lower res textures are not fanboys, they just know hardware and can do math. Please only comment if you know what you are talking about, and thank you for reading this far! ;)
