Ok ... well well well ....
In fact, what i need is something like a LED projector.
I need to power all the LEDs at the same time and @ 700mA (knowing that @700mA , they have a forward voltage of 2.4v).
I need about 200watts of LEDs ; knowing that a 3W LED will never run at this power consumption, they will mostly run @70% of their capacity, this is why i wanted to have ~150x 3W LEDs ...
By the way, i could buy some led drivers on eBay, but i don't know if these models are reliable enough (in time).
I even don't know how many heat they produce.
There is a lot of "i don't know" in this history.
Rolling over on eBay, i found this item : http://www.ebay.com/itm/320584715555
3A ... of constant current on about 100W ... i could drive a lot of LEDs with this !
If i drive 5 similars rails of LEDs, i could expect approx 600mA of current, which is good for me. (i could optimize their lastlife).
What do you think of this ?
PS : after reading your post, now, i doubt it is even possible ... OR, is it possible to drive the LEDs on a parallel basis with this kind of constant current power supply ?