Running COB LED without driver (undervolted)
Oh for pete's sake:


You can't "under volt" an led.  Too little voltage and it won't turn on at all.
If you try to put leds in parallel, then you must provide each parallel line with its own current limiting.
You must use current limiting to drive your leds.  An led operating at just over its forward voltage will draw just a little current.  At a slightly higher voltage it will draw much more current - enough to burn out.
Leds of that type are typically operated with a constant current power supply.  The voltage range you listed is the range in which the power supply can maintain the desired current.


Leds are not like light bulbs, despite the fact that both produce light.  Read up on them before you destroy a bunch by treating them like incandescent light bulbs.



You can't operate a 32Volt led on 24 Volts.  You must get the voltage up to the minimum forward voltage, and then limit the current.

The simplest way would be to get a proper power supply.

To use your current power supply, you must use a boost regulator to generate a higher voltage.  You then either use a series resistor to limit the current, or you use an active current limiting circuit - which a proper power supply will already have.