That spikes must be  thermal downclock. I see exactly same spikes when my environmental air are over 20 deg. That make me think the aluminium cooler for chips are too small and chips always work on they limit temp and often are downclock to prevent overheating(that also lover the hashrate)

Now i make some spimle air duct. Sp 20 suck cold air from outside and heat our room where we put our flowers during winter to prevent them from freezing.

The asic keep the room +10 degrees wich is perfect for the plants 

Ps. i didn't hear any plant to complain about noise till now