@ronvalencia said:
1. 7770's ~1.0 billion triangle per second vs X1's 1.7 billion triangle per second.
2. 7770's 72GB/s memory bandwidth vs X1's 68 GB/s memory bandwidth + 204 GB/s ESRAM (~165 GB/s for read and write from 16 ROPs).
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PS4's 32 ROPs wouldn't be fully utilized i.e. it's gimped by it's 176 GB/s (theoretical) memory bandwidth.
7950 has the same 32 ROPs as PS4, but the 7950 BE has higher 240 GB/s (theoretical) memory bandwidth to support it's 32 ROP's read and write memory operations.
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http://www.tomshardware.com/reviews/768-shader-pitcairn-review,3196-5.html
Prototype Radeon HD 7850 with 12 CU or 768 stream processors with 153.6GB/s (theoretical) memory bandwidth.
•12 Compute Units (CU) at 860Mhz
•48 Texture Units (TMU)
•768 Shader Cores
lol No. It does NOT have 48 Texture units. It has 64 compared to the X1's 48. Check out the comparison sheet on Page 2 of the article you linked.
I also like how you conveniently forgot to mention that this 7850 they are using to test has 32 ROPs instead of 16 that the X1 has.
If anything this proves my point that having more Texture Units (PS4 actually has 72), more Shader units (1152) and more ROPS (32) will result in a pretty substantial performance difference.
You do bring a good point about the 7770 having only 72 GB/s memory bandwidth. That's something I completely overlooked. However, I'd highly disagree that the X1 has 270 GB/s memory bandwidth like the X1 architects having been talking about. The ESRAM can do 109 GB/s, but you simply cannot add up the DDR3 bandwidth and the ESRAM bandwidth. Quite a few tech websites like Anandtech and Arstechnica have questioned MS's claims. MS did walk back on it in the DF interview and said it's close to 134GB/s in their 'tests'.
Fact is that devs HAVE been bitching about the ESRAM and you can ask anyone who is not a MS employee and they would pick GDDR5 over ESRAM any day of the week and twice on Sunday.
Lastly, my comparison favored the X1 by a good 200 Gflops and it still blew it away. The Tflops number on the 7770 is 1.28 while the X1 only has 1.18 available for gaming. The Tflops number on the 7850 is 1.76 while the PS4 has 1.84 Tflops. So this comparison was skewed more than 200 Gflops in X1's favor.
And before you say Tflops number does not matter, it takes the stream processors and the clock speed into account.
853*768*2=1.31 Tflops for the X1.
800*1152*2=1.84 Tflops for the PS4.
My comparison had the 7770 running at 1000 Mhz and the 7850 running at 860 Mhz. If you use MS's own claims that increasing clock speed gives a bigger advantage than adding CUs (more stream processors, more texture units and potentially more ROPs) then you shouldn't have a problem with that comparison.
1000*640*2= 1.28Tflops for the 7770.
860*1024*2= 1.76Tflops for the 7850.
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