You use one of the power boards per cob (leds), you can run multiple cobs off a power board though so long as its in parallel but all your doing there is dividing the power each one gets
1x15w board = 1x15w to the leds
1x15w board = 3x5w to the leds if say running three cobs so they would be only be around 33-40% as bright each “lower the power the higher the efficiency typically”
And no the boards were wired to 120Vac “parallel to a standard power cord” as those boards need 120v to function as that is how they are designed as far as how they are before dismantling.
But probably the question you were wondering, i also had a 12vdc wall power converter wired up to that 120vac cord, it powered the fan and arduino stuff.
Guess i dont have a picture of the top in here but this was after a change and my Version 2, 12v power converter that was deboxed on the bottom right, 120v power cord going out the left, and 120v going to the power boards of the leds, but going through a relay first just for timer purposes.
You can find more info about it im my other thread Micro Growing with Mr. Sparkle *2018* will be posts from january to april of this year
