So I just took my last readings for AS5 vs MX-4 on the CPU-360...
My testing process was as follows using prime95 for loading and only showing 1 window on desktop to ensure I'm not adding inconsistent heat from GPUs
-15min @100% fan speed full load (ignore results)
-15min @100% fan speed idle (ignore results)
-15min @100% fan speed full load take measurement
-15min @100% fan speed idle take measurement
-15min @40% fan speed full load take measurement
-15min @40% fan speed idle take measurement
Temperature below = delta above ambient (or at least what I used to record ambients)
@100% Fan Speed
AS5
Idle: 2.8'c
Load: 13.8'c
MX-4
Idle: 2.8'c
Load: 14.3'c
@40% Fan Speed
AS5
Idle: 4.8'c
Load: 17.0'c
MX-4
Idle: 4.8'c
Load: 17.5'c
In short for what I did they are equivalent products at idle however under full load I was able to see upwards of 0.5'c difference in favor of good ol' capacitive AS5. However with two 6990's being in the same loop, and a radiator as big as the one I have there is always some margin of error. But running the tests multiple times I got pretty consistent results.