Successfully modded a X11SPL-F rev 1.02 using Adafruit MCP2221a and BIOS 3.9 255W. CPU used is a slightly dead 8259CL and a slightly ECC challenged 32 GB Samsung DDR4 RDIMM from the trash bin.
Procedure was to just put the CPU in, turn on power so IPMI boots but not the system (CPU fan off). Run a scan using Microchip's terminal to see if SDA SCL GND are connected properly. GND is 0 Ohm to the USB connector housing shield, so easy to spot with beeping multimeter. Terminal should find around 10-20 addresses. Then run the patcher. Power-off power-on. Continue with BIOS...
Since the terminal is Windows only here is a script to attach and detach the MCP2221a device to a Windows VM on Linux KVM:
Bash:
#!/bin/bash
VM="YOUR_WINDOWS_VM_NAME_HERE"
USB1=$(virsh dumpxml $VM 2>/dev/null | tr -d '\n' | grep -Ei 'vendor id=.*04d8.*product id=.*0x00dd')
USB2="\
<hostdev mode='subsystem' type='usb' managed='no'>\
<source startupPolicy='optional'>\
<vendor id='0x04d8'/>\
<product id='0x00dd'/>\
</source>\
</hostdev>"
if [ -n "$USB1" ]; then
echo $USB2 | virsh detach-device $VM /dev/stdin
else
echo $USB2 | virsh attach-device $VM /dev/stdin
fi
exit 0
Edit: Power meter says 4.5W with only Aspeed BMC running, 52W Linux idle + empty (1 RAM Stick, 1 USB-Stick for booting Linux, 1 USB-Stick for Wifi).
Hottest chips at idle are the AST2500, a companion low-dropout RT9018B regulator (+5V ATX standby to what AST needs I presume), and a Realtek network chip also for the AST. Southbridge a hot mess, seems cooler than on Asrock. Other stuff is coils getting warm.