Observations on AMD GPU memory clocks

During the recent E@H work outages, I've been switching to Milkyway@Home GPU tasks and found some interesting differences in GPU performance between the Projects. The difference that first caught my eye was quite a bit lower GPU temperatures when running M@H tasks compared to E@H tasks. I then realized that both my AMD RX 460 and RX 570 run E@H at the top memory clock speed (1750 MHz), but run M@H at the lowest Mclk speed (300 MHz).
I noticed that the cards were also running at higher clock speeds (shader clock or core clock). The cards carried over the power caps I was using for E@H, so I tweaked the cards' power caps and ended up running M@H on the RX 460 at its max shader clock speed (1172 MHz) using a power cap of 44 W (vs. 48 W max). I set the RX 570 at near its max shader clock speed (1250 MHz @ state 6 vs. max 1286 MHz @ state 7) using a power cap of 105 W (vs. 125 W max). I adjusted the RX 570 power cap to that particular setting because I didn't notice any decrease in M@H task time with higher power that allowed the max clock speed.
The upshot is that I learned, perhaps what some folks already knew, that a sizeable chunk of the power for running E@H GPU tasks comes from running the card's memory clock at top speed. i haven't messed with underclocking memory. 
I have a Ubuntu system with AMDGPU open drivers and did all GPU performance monitoring and power capping with the utility amdgpu-utils https://github.com/Ricks-Lab/amdgpu-utils. I assume similar results could be seen under Windows with AMD Wattman.