I just stripped out my water loop to clean it. I think I was like, 2 months past due for a coolant exchange.
The result: there was growth in the loop.
So I dismantled the entire loop to its individual components, and I'm soaking the inside of my radiator in a 1:1 mixture of water and white vinegar to kill anything that's in the radiator.
Plus the computer needs a thorough dusting.