I have a 23 x 39 inch space and I am planning on buying a 240W quantum board.
Does this have a proper illumination for this space? Because they are way cheaper then the samsung strips.
Your space is 23"x 39", about six and a half square feet. You want a minimum of 30 watts per square foot to flower.
6.5 x 30 = 195 watts minimum. A 240w board (hopefully with a dimmer) would do the trick.
The only issue I see is with coverage. A 320 watt quantum board would cover the area better, three foot heatsink. The boards run more efficiently and last longer if you run them at 80% or less. You could run a 320w board at 80% power, put 260 watts over 6.5 square feet, 40watts per square foot. Bingo bango.