Power supply for 5*10 watt SMD LED?
Here's a way of learning about the LEDs and improving your electronics knowledge.

LEDs are diodes and they exhibit a non-linear relationship between the voltage applied to them and the current through them. See the graph below. What this means is that as the voltage increases the current increase exponentially and we are in danger of smoking the LEDs.



To get around this problem we limit the current through the LEDs either with a resistor or a constant current power supply. Either way the current is limited to a safe value.

The next problem to address is that if the LEDs are paralleled as in your diagram uneven current distribution will occur. Due to manufacturing variation some will pass more current at a given voltage (and they all share the same voltage in your circuit). The one that's passing most current will heat up more than the other, allowing even more current through it, etc., until it fails. The pattern will repeat and you may blow all the LEDs.

If you wish to pursue this the best thing would be to get your hands on a bench power supply - borrow or go somewhere where you can use one for an hour and proceed as follows:




Solder wires to the lugs of the LED.
Mount the LED on a heatsink. 10 W is huge power for such a small die and you need to carry the heat away. You'll need thermal paste.
Set the power supply voltage to 12 V. Set the current to zero.
Connect the LED observing polarity.
Switch on the power supply output. The voltage should drop to zero since you have set a zero current.
Turn up the current slowly. You should get plenty of light by 100 mA and the voltage should have risen. Make a note of V and I.
Repeat in 100 mA steps up to 1000 mA checking your heatsink temperature.
If you have time, repeat the procedure for one or two more of the LEDs.
Draw a graph and post it here (as an update to your original question).


You should get help then.

LED tutorial