Home Assistant runs on a dedicated small form factor pc, a HP Prodesk 405 G6.
The specs of the pc:
Brand: HP
Type: Prodesk 405 G6
Processor: AMD R5 Pro 4650GE
Memory: 8Gb
Harddisk: 512Gb M2 SSD
Attached via USB are a Sonoff ZBDongle-E Zigbee dongle, a Bluetooth dongle and a RFXcom RFXTRX433XL dongle for 433Mhz communication.