When you use 24V power supply and 6 leds per 1 lm317 connected to resistor there is a limit factor. You can use more power than you need but not less. The led unit will draw what it needs. So if you have 500w supply and the leds you have only draws 100w then it will only draw that much power nothing more.
[How much can leds you connect with a single LM317/resistor ]
32V driver (8) leds
24V driver (6) leds
12V driver (3) leds
If you want to use 3W LEDs you will need 1.8 ohm resistor -/ which is equal to 695mA
(200pcs/lot) 1.8 Ohm 2W Watt 5% Carbon Metal Oxide Film Resistor
http://s.aliexpress.com/EB77nmeU?fromSns=Copy to Clipboard
To calculate what power supply you need to multiply ranks(6 led per rank) x mA = Amp
Example
8 ranks (6- 3w led per rank) X 0,7 A = 5.6 Amp
24v driver x 5.6 = 134.4
Make sure u have 10% power on the driver extra and for this reason i would get a 24v 200w driver. You can get 150 but to be careful i would go for 200w as they dont come in 180w/190w etc.
Do not forget each channel on the tc420 has a 4 amp max rating so to calculate this for 3w led/
5 Ranks (6 leds per rank) x 0.7 = 3.5
24v ( power supply) X 3.5= 84w
So this means max you can do is 4amp so you can only create 5 ranks per channel which is 84w and 84w x 4 channels = 336 w totals. So tc420 can handle 480w even more but to be safe 336w would be good enough as we using resistors and drivers.
As you can see the diagram i drew has 96 1w leds and 16 ranks all together.
16 x 0.3 ma = 4.8
24v x 4.8 = 115w
Power supply used was 6.5 amp 150w.
Ofcorse the number of leds is 96 and that is 96w but the led unit will draw more power something like 115w depending on how you dimmer the lights.
Let me know what you intend to make and i can draw a sketch for you as i do not have a pc atm.