ChiefDada
Member
Preface: THIS THREAD IS FOR THOSE INTERESTED IN TECH ANALYSIS/DISCUSSION OF RDNA 2 AND THE DESIGN CHOICES FOR PS5 AND SERIES X. NO CONSOLE WARS PLEASE!
https://www.computerbase.de/2021-03/amd-radeon-rdna2-rdna-gcn-ipc-cu-vergleich/2/
Awesome analysis that I think is the most comprehensive in comparing RDNA 2 CU scalability between AMD 6000 series cards, all fixed at 2ghz clock frequencies. Results posted below, but I wanted to point out a crucial point from a different but related test they conducted that determined RDNA 1 CUs are actually faster than RDNA 2 CU due to the shorter ALU pipeline (this should serve as a reminder to some that RDNA 2 isn't inherently better than RDNA 1 across the board AMD) .
Applying the findings below to the premium consoles, there are a few interesting facts from my perspective:
1. Cerny's argument of CU utilization doesn't pan out in the games tested below. CU scalability remains relatively constant from 1080p-4k. Although it is possible that current gen games could yield a different outcome.
2. Series consoles chose RDNA 2 design with inherent CU latency increase compared to RDNA 1, without offsetting via higher clock frequency (2ghz+) as AMD and Sony have done with 6000 series and PS5, respectively. Based on the testing, it doesn't appear as though Series X 560gb/s throughput would be enough to compensate to achieve the levels AMD was able to with faster clocks/cache. As shown below, A 50% CU advantage AND 33% bandwidth advantage for the 6800 over the 6700xt resulted in only 36% performance increase at 4k (again, both GPU clock frequencies fixed at 2ghz). Series X has 44% CU advantage and 25% bandwidth advantage ceiling over PS5 with its fastest memory segment. If anyone has information as to why Microsoft deviated from AMD RDNA 2 strategy, I would be interested to learn about this (proprietery hw/sw, etc.).
Data Parameters
1080p Performance
1440p Performance
4k Performance
https://www.computerbase.de/2021-03/amd-radeon-rdna2-rdna-gcn-ipc-cu-vergleich/2/
Awesome analysis that I think is the most comprehensive in comparing RDNA 2 CU scalability between AMD 6000 series cards, all fixed at 2ghz clock frequencies. Results posted below, but I wanted to point out a crucial point from a different but related test they conducted that determined RDNA 1 CUs are actually faster than RDNA 2 CU due to the shorter ALU pipeline (this should serve as a reminder to some that RDNA 2 isn't inherently better than RDNA 1 across the board AMD) .
RDNA 2 clocks significantly higher than RDNA and achieves a not insignificant part of its additional performance from it. In order to reach the higher frequencies, the pipelines within the ALUs were lengthened, among other things, which increases the latencies and thus reduces the computing power per CU with RDNA 2 compared to RDNA, despite actually having the same capabilities for latency-sensitive calculations.
RDNA 2 has slowed down a bit
You can see that in the tests. RDNA 2 is on average 4 and 5 percent slower than RDNA with the same computing power. At the same time, this also shows that the longer pipelines for RDNA 2 were a good decision. In practice, this 4 percent reduction in computing power is offset by a clock rate that is around 24 percent higher for Navi 21 (RX 6800 XT) and a clock rate that is around 40 percent higher for Navi 22 (RX 6700 XT) - a good exchange: IPC for frequency.
Applying the findings below to the premium consoles, there are a few interesting facts from my perspective:
1. Cerny's argument of CU utilization doesn't pan out in the games tested below. CU scalability remains relatively constant from 1080p-4k. Although it is possible that current gen games could yield a different outcome.
2. Series consoles chose RDNA 2 design with inherent CU latency increase compared to RDNA 1, without offsetting via higher clock frequency (2ghz+) as AMD and Sony have done with 6000 series and PS5, respectively. Based on the testing, it doesn't appear as though Series X 560gb/s throughput would be enough to compensate to achieve the levels AMD was able to with faster clocks/cache. As shown below, A 50% CU advantage AND 33% bandwidth advantage for the 6800 over the 6700xt resulted in only 36% performance increase at 4k (again, both GPU clock frequencies fixed at 2ghz). Series X has 44% CU advantage and 25% bandwidth advantage ceiling over PS5 with its fastest memory segment. If anyone has information as to why Microsoft deviated from AMD RDNA 2 strategy, I would be interested to learn about this (proprietery hw/sw, etc.).
Data Parameters

1080p Performance

1440p Performance

4k Performance
