For the Purple Fan LEDs, I would recommend a more substantial heat sink, and a high static pressure fan, especially for higher power leds (anything over 3W, imo is high power). Treat it basically like a CPU.
If you have a high power led and it isn't that hot, then it is likely not running at full capacity, you could have just bought a cheaper, lower power, higher quality led, either check the draw on it.
Personally when I used a 10w led running properly, I had to use liquid cooling. My guess is that the leds are probably only running around 15-18W total maybe a little more.
Fans and heat sinks aren't too expensive and it will save the life of the leds, and allow them to preform better.
If you have a 3 axis mill, you can make heatsinks in a few mins, and its super cheap, it looks like you have access to some tools.
The fans look like they are in the intake configuration in this case it is less efficient, since heat is rising and the fan is pushing that heat back on to the led.
On a more detailed note heat does effect the band gap in the semi-conductors, which in turn effects the emitted wavelength, if this has a discernible effect on plants I have no idea, but its just another reason to keep it cool.