24v COB rgb 840 strip controled by Raspberry Pi

My apologies  fskrzycki for my response on using modules solutions to solve problems consuming your post. That was never my intention. 

You being a new member, it does provide an example of the potential the E14 Community provides. You will need to develop the ability to keep from getting upset or offended by the things other people say and do. You have to have a thick skin when it comes to criticism. Most responses are OK but with 700K members there may be some responses that reflect a lack of emotional intelligence.

I remember one of my early forum adventures when I tried to help out a fellow member with my limited knowledge. I suggested a simple solution, and then this person got all fired up and replied, "Some of us solder components!"  My kids still crack up about that post. 

There's no detail in the diagram, somehow it has been inserted as a tiny image.

Could you upload the diagram using the Insert menu item, then select "Image/video/file", and then you'll be able to choose the image file.

Currently, the image looks like this zoomed in:

Also, what is the part code (or web link) of the MOSFETs? A photo of the setup will help too.

That helps a lot. Based on that, if the circuit so far is successfully operational, then the LED strip is known as common anode (not common ground), which helps understand the circuit.

The circuit below shows how to insert the PC817. Notice that the Pi's GND is completely isolated from the 0V connection which will be connected to your LED strip's power supply brick.

With the PC817, the output will be inverted, i.e. you'll have to set the GPIO high to turn off the LED and vice-versa. There's no clean way around that, without changing the design, or inserting more parts (refer to the earlier diagrams to see how that is done). Rather than that, it should be a trivial change to edit the Python code to invert the logic.

Every component in the diagram below is essential. If you're using a PC817 module (as opposed to just the PC817 component) then, as discussed earlier, the module has some issues. You'd need to remove the LEDs on the PC817 board, and you'd need to replace the 1k resistor on the board with 220 ohms as shown in the sketch here. It would be easier to just buy the PC817 component and not the module, but modifying the module as mentioned would fix it.

i understand. Just to be clear the circuit above is for one color only.. if I go with using the 817 component, can I use the same gpio ground pin for each color? 

Can the overvoltage protection be the same component in the example above? I think you have the Gate/Source/Drain on the MOSFET mislabeled. can you double check 

i may be over thinking this, but it looks like i dont need the MOSFET at all. what would the circuit look like without it? 

Correct, only one channel is shown since they are all identical. All the 0V connections will be common together. All the Pi ground connections (GND) will be common together (GND will not be connected to 0V; they are isolated).

Every pin labeled ground on the Pi's header is electrically connected to each other (you can verify with a multimeter set to ohms on an unpowered Pi if you like). It makes no difference if you use a single ground pin, or separate ground pins for the project.

The zener diode protects just the MOSFET. The PC817 protects the Pi by isolating it, since there are zero connections from the Pi that are present on the right side. The GPIO and the Ground from the pi on the left are totally isolated beyond the LED inside the optocoupler.

The labeling on the MOSFET in the sketch above is correct. Without the MOSFET, this can't work. the PC817 does not have the output capability to operate the strip.

You could remove the entirety of the circuit with a 'neopixel' style LED strip as mentioned earlier. The strip you currently have will need the parts shown above, if you want the PC817 isolation.

thanks, what wattage level resistors would you recommend? 

1/4 W is fine for them all, or even 1/8 W.

1/4 W is fine for them all, or even 1/8 W.