WARNING More rambling follows!! Skip this one if you value your time.Warning my rambling follows!!
As I remember each led requires voltage and current to turn on. When I was making led strings I could only use up to 3 reds, 3 greens, or 5 reds on a 12 volt string. yack yack yack
I did goof a little, I was referring to dumb single color led's. I was only referring to the voltages required for a single color led, and not to a smart string. Inside a smart string pixel is at least 3 led's 1 red, 1 blue, and 1 green inside a single package. These are not in series. Some pixels have, what is called, 3 or 4 led's. In my ramblings this would have been 1 string of red, 1 string of blue, and 1 string of green, consisting of 3 or 4 led's in series. Smart string pixels calling out 4 led really have 12 leds.
OK if I have 12 volts how many blue led's can I light up? We will power a string of blue led's with 17.3mA from 12 volt power. 17.3mA X 12Volts = .2076 Watts. This will give us .2076 Watts of total power for a string of blue led's. Each blue led at 17.3mA will require 3.3 Volts, or .0571 Watts.
A string of 1 blue led's will require .0571 Watts of power, 1 X .0571 = .0571 This is less than our available power of .2076 Watts. OK. The extra power of .1505 Watts will be used to keep things happy.
A string of 3 blue led's will require .1713 Watts of power, 3 X .0571 = .1713 This is less than our available power of .2076 Watts. OK. The extra power of .0363 Watts will be used to keep things happy.
A string of 4 blue led's will require .2284 Watts of power, 4 X .0571 = .2284 This is more than our available power of .2076 Watts. No extra power. Problem. The string may act up. This means that you require more voltage or more current. Increasing the current will blow the led's. If you increased the voltage to a smart string, you may blow the pixels.
And yes these numbers are in the wiki. This is even the numbers used for the pixel squares. "But they don't match!" Yes they do. There are 3 colors in 3 led strings of 3 led's each, for each pixel. 17.3mA for red, 17.3mA for green, and 17.3 mA for blue. 17.3mA X 3 = 52mA. We have a match.
All of this is the same for the green led's. The red is a different story. Red will be ok at 4 led's.
The extra power from each string of led's keeps everything happy and stable.
1 led's per color string pixel has .1505+.1505+.1730=.4740 Watts, all 3 colors happy with 76.1% Extra power available.
3 led's per color string pixel has .0363+.0363+.1038=.1764 Watts, all 3 colors happy with 28.3% Extra power available.
4 led's per color string pixel has -.0208-.0208+.0692 =.0276 Watts, 2 colors may act up, only red happy, with 4.4% Extra power.
The simplest way I know to figure this all out is, power supply voltage divided by led required voltage = max leds in series.
example
12 volt / 3.3 volt = 3.6 led's max. I can't have a .6 led, so I round down. The 3 led's will require 9.9 volts, leaving 2.1 volts to keep things happy.
The wiki shows 52mA per pixel, 80 pixels max for a smart string 80 X 52mA = 4.16 amps for a full string. With all pixels on full white, there will be a voltage losses on the pixel string flat wire, in the smart string controller, the cat5 cable, hub, and power supply. If it is just .2 volt total loss, we have lost 1.7% of the power available for the pixels to use.
All of this is with pixels just full on, no dimming, no pixelnet data, no tm1804 data. The power gets marginal. Throw in pixelnet, and 1804 data, pixels dimming, now you have noise on a marginal power system. Non of this is good. When things are marginal problems are likely to show up. What fixed it 1 time may not the next. Every thing may be fine on the bench, during tests. do you really want to be troubleshooting things in the yard, at night, in the dark, and the weather.
Lets stick with things that work. For me that is 3 leds per color, per pixel on 12 volt power max. Or No more than 3 led's in a pixel on a 12 volt string.
Of course that's just me.
My apologies for this being such a long read, I hate trying to explain things without seeing feed back. I tried to keep it short the first time, and I fear this may make thing worse. I tried.