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@tormentos said:
@ronvalencia said:
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I don't need a link since TMUs and ROPs are units that consumes memory bandwidth and can be calculated e.g. ROP's and TMU's bytes per cycle rates.
None of the PC hardware has shown a prototype 7850 with 12 CUs (768 stream processors with 48 TMUs) and 153.6GB/s memory bandwidth.
Disabled CUs doesn't change the fundamental processing power of the device i.e. it will remain about 1.3 TFLOPS at 860Mhz from 12 CUs.
For read and write ROPs, 7790's 96 GB/s bandwidth wouldn't even fully use it's 16 ROP's Gpixel rate e.g. 165 GB/s.
http://www.tomshardware.com/reviews/768-shader-pitcairn-review,3196-5.html
If 60 fps was the target frame rate, anything less than 7950 would need to reduce the render resolutions.
Oh yes you need to because you are making arguments based on your opinion,i am making mine based on fact,
The xbox one has a 7790 with 2 CU disable is not a prototype 7850 that card didn't have 14 CU it had 12,the xbox one has 14 with 2 disable,and the regular 7850 has 16 and both 7850 had 32 ROP.
So yeah it is not.
No dude and it has been argue that 2 CU more at 800mhz would have been better than 6% GPU upclock.
The xbox one doesn't have a full 7790 so needing 165Gb/s is even less relevant,even more at resolutions lower than 1080p which is the case with BF4 and several other games,
For 1.18TF you don't need 165GB/s bandwidth or it will serve you for anything,mind you that MS claimed 140GB/s to 150 GB/s that is what you will get no 204GB/s,so yeah even your 165Gb/s number would saturate that banwidth.
In the end i told you so having a weak GPU with high bandwidth will not change anything,BF4 720p just confirmed that.
LOL, You haven't notice X1's has modified it's internal crossbar/bus to support
1. four 64bit channel DDR3.
2. full duplex four 256bit channel ESRAM.
The 7790 has a bottleneck that doesn't enable it use faster memory. Are you so thick that you can't calculate 64 byte per cycle from it's L2 cache?
Your "1.18 TFLOPS you don't need 165 GB/s bandwidth" statement is BS. 165 GB/s comes from ROP's raw read and write requirements NOT CUs. Your mistake.
The prototype 7850 with 12 CUs at 860 Mhz indicates otherwise. Both prototype 7850 with 12 CUs and X1's 12 CUs has similar TMU load/store patterns.
You haven't calculate the raw memory bandwidth to feed the 1.18 TFLOPS.
Each CU's L1 cache has 64byte per cycle rate and there are 12 CUs i.e. that's ~610 GB/s of raw bandwidth. Your second mistake.
The big problem with current GCN design is when workloads overspills beyond CU's SRAM. Outside of the CU, you hit design issues like L2 cache bandwidth and it's memory controller's I/O width and overheads.
GCNs like 7970 has more CUs hence more internal SRAM storage before performance degradation. Lesser GCNs like 7850 encounters performance degradation quicker than 7970.
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Xbox One does NOT have a retail "7790" since it (the 7790) doesn't have X1's memory setup.
7790 = 96 GB/s memory bandwidth from it's 128bit GDDR5. This memory bandwidth is shared between it's TMUs and ROPs.
X1 = 68 GB/s DDR3 and 204 GB/s ESRAM. This memory bandwidth is shared between it's TMUs and ROPs.
Both X1 and 7790's numbers are theoretical values.
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Lets assume DDR3 ~= GDDR5 in terms of overheads/efficiencies.
X1 = 55 GB/s DDR3 and 150 GB/s ESRAM. 55/68 = 80 precent efficiency.
7790 = 80 precent efficiency on 96 GB/s = 77.64 GB/s.
7770 = 80 precent efficiency on 72 GB/s = 57.6 GB/s.
7850 = 80 precent efficiency on 153.6 GB/s = 122.88 GB/s.
If we use your logic, we'll be claiming R600 codename for Radeon HD 4670 (RV730) LOL.
Disabled CUs does NOT change computation performance i.e. they are inert units. Your PC relative GPU selection doesn't come close to X1's CU (ALUs+TMUs) with memory setup.
What's more important are the following
1. working CUs count since this influences CU's TMU load/store pattern, wavefront buffer size, L1 cache size, LDS size, branch/scalar processor count, total L1 cache byte per cycle rate and 'etc'.
2. closest memory setup to X1.
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As for sub-1080p, both consoles has lesser GCN solutions than the 7870 GE replacement i.e. R9-280X.
Both of my 7950 (900Mhz firmware) and 7970 (925 Mhz firmware) are overclocked to 1 Ghz. AMD basically made my 1Ghz overclocked 7970 official i.e. 7970 GE and R9-280X.
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