Computing SHA256 hashes at 820 KH/s draws 4 Watts, ... ( 13:42 ) but he has some problem with the serial I/O ( 13:01 ) that I don't understand. Maybe it's with the Windows driver? Here's his video about using the Nanjing Qinheng CH382 PCIe serial interface chip on an M.2 board to make an LED matrix: CH382 is a PCI-Express bus converter chip, which converts PCIE bus to dual serial ports and printer port, including two asynchronous serial ports compatible with 16C550 or 16C750, and one EPP/ECP enhanced bidirectional parallel port. The asynchronous serial port provides a transceiver with independent 256-byte FIFO buffer, supports communication baud rate up to 8Mbps and can be used for RS232 serial port expansion of PCIE bus, PCIE high-speed serial port with automatic hardware flow control, serial ports networking, RS485 communication, parallel/printer port expansion, etc. See https://github.com/bitluni/Mdot2Matrix . Subscribe to Bitluni .