Hi, can you please post a picture of your project and a CAD or picture of your circuit diagram please.
Also post your sketch. use code tags.
Have you got the led's assembled on a protoboard,the strip conductors can be a problem with high current use.
Its sounds like your power supplies for the LED does not have enough filtering or regulation.
Can you measure the LED supply voltage for us, one with the LEDs flickering and one with them not, ie higher duty cycle, thanks.
You have asked us for help, its your project so you are miles ahead with understanding how its assembled. Pictures will help us get up to speed without misguided advice.