SK6812 Flicker Rpi3B

I have a Pi3B running 2.0.14

Pixels: SK6812 GRB (NW)

Pixel count: 262, 84 top and bottom and 47 sides

Pixels and Pi are running off a 350w meanwell dialed in to 5.1v(5v at lights after vdrop).

Magewell HDMI plus capture card and HDMI DA running off the Pi usb power.

The cable going from the pi to the lights isn't super short so I added a logic level shifter.

In the past I had been using ws2811 and the flickering was cured by adding the level shifter.

Ground and 3.3 from the pi pins to the LV side of the level shifter. The HV side of the level shifter comes directly off the PSU.

I have modified the cmdline.txt

spidev.bufsize=1024000

I have modified the config.txt

dtparam=audio=off

There is a sporadic flicker and the first pixel frequently stuck on green or sometimes off and occasionally stuck on a random color but this is much less frequent..

I had a Pi 4 laying around and decided to try it from that unit. It has more horsepower so I clocked it higher and this is what I've got and its perfectly stable not a single flicker since the change

LED Output:

Baudrate 3600000

Only copied the fields I edited.

cmdline.txt:

spidev.bufsiz=65536

config.txt:

#uncomment to overclock the arm. 700 MHz is the default.

over_voltage=2

arm_freq=1750

# GPU Overclocking

core_freq=650

core_freq_min=650

# Uncomment some or all of these to enable the optional hardware interfaces

#dtparam=i2c_arm=on

#dtparam=i2s=on

dtparam=spi=on

# Enable audio (loads snd_bcm2835)

dtparam=audio=off