Sync room lighting with multiple power sources

Hey guys, I'm in a bit of a struggle here...
I wanna have my full room led lit, ambilight, PC case lighting, closet and everything, wich I was able to set up... For the most part.

I am currently controlling most parts separately, with independent Arduinos and power sources. But since controlling all of them got kinda complicated, I wanted to connect them all. Either wirelessly, but that might get expensive, so if possible, something else would be appreciated, or I simply connect all the Arduinos together/all the LEDs to one Arduino.

The problem is: the Arduino has to be connected to the pc via USB, and I don't have a PSU powerful enough to drive all the LEDs. Can I power some of the LEDs with an external PSU if I connect all the grounds together? Since the potentials would be equal, I wouldn't have any signal problems, but wouldn't such an approach lead to relatively hight current flowing between my power supplies???
I appreciate any help, I'm mainly just worried to fry my PC PSU by doing that, since I draw part of the power from my molex 4-pin connectors and the additional current flowing might hurt it... As I said, I don't know how to approach this... :confused:

Can I power some of the LEDs with an external PSU if I connect all the grounds together?

Yes.

But what sort of LEDs are we talking about? WS2812b strips? Or more conventional 12V none addressable strips?

Yeah, WS2812b individually adressable LEDs

since I draw part of the power from my molex 4-pin connectors and the additional current flowing might hurt it

Does it heat up or produce a significant voltage drop either side of the connector? If no to both then you are OK.

Oh, ok.
I didn't test it yet, I just didn't wanna break anything so I asked in advance.

Yep, works, thanks :slight_smile: