Many of Us are Using CPU Heatsinks and Cooling Fans to Cool COBs
These are awesome, but they're designed to be plugged into a PC motherboard or power supply. So the question becomes, where do you get a 12V DC power supply that works? The CCTV industry, that's where. CCTV cameras are mostly 12V DC powered, and the industry now has many manufacturers of transformers. The down side is there are a lot of cheap transformers which are a waste of money.
Do your research, find a quality company with a quality product.
I Found These UL-Listed Transformers and They're Working Great
My fans are 3w and .25 amp, so I'll be able to run 3 fans from each transformer and be a quarter amp below maximum. I'm safe with even UL-listed devices. These power supplies are now running one fan cooling 60w over beet and spinach sprouts, and two 50w cobs over some cannabis. I tested the remaining 3 transformers today and they're also in working condition. (Thank You!!)