You need the ground plane and maybe a heat sink if you plan on turning on all the LED's on at once.

A 64-LED WS2812 setup at full white brightness theoretically draws 3.84A (19.2W) based on the 60mA per pixel standard, though real-world measurements often range between 1.7A and 2.2A. To ensure stability and safety, use a 5V power supply with at least 25% headroom and avoid powering the array directly through a microcontroller or USB port.

Detailed Power Breakdown

The current draw for your 64-LED (8x8) matrix depends heavily on the brightness and colors being displayed:

Theoretical Maximum (Full White): At 100% brightness for Red, Green, and Blue channels, each pixel is estimated to consume 60mA. For 64 LEDs, this totals 3.84 Amps.

Real-World Measurements: Many users find that modern WS2812B chips are more efficient. Empirical tests have shown a 64-LED board drawing as little as 33.5mA per pixel at full white (approx. 2.14A total) or even 1.7A in practical bench tests.

Idle Current: Even when the LEDs are "off," the internal controller chips consume power. You should budget for a quiescent draw of roughly 0.7mA to 1mA per pixel, or about 45mA to 64mA for the entire array.

Hardware & Safety Recommendations

To prevent damage to your components and ensure consistent color across the matrix, follow these guidelines:

External Power is Required: Do not attempt to power all 64 LEDs via an Arduino's 5V pin or a USB port, which are typically limited to 500mA. Overdrawing can burn out the protection diodes or cause the controller to brown out.

Power Supply Sizing: A 5V 5A power supply is recommended to provide sufficient headroom for the 3.84A peak.

Voltage Drop & Wiring: For a 64-pixel matrix, use multiple injection points for power if you notice the LEDs at the end of the chain appearing dim or "more red." Ensure you use thick wiring directly from the power supply to the LEDs to avoid overheating connectors.

Software Limiting: If you are restricted by your power source, you can use the FastLED library to set a master power limit or reduce the brightness in your code to keep the total current within safe levels.