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You can remotely start a PC without Wake-on-LAN by using an ESPHome-controlled relay to briefly close the motherboard’s power-switch circuit. The relay imitates a tap on the case’s power button; it does not send a network wake packet. Whether it works depends on the specific board, its wiring and firmware configuration. The cited device guides do not establish a current $3 price, so treat that figure as unverified.
How the relay starts the computer
A PC case’s power button is a momentary switch connected to a motherboard header. A relay wired across the corresponding power-switch contacts can imitate that brief closure. An ESP32 then activates the relay for a short pulse when you trigger it through ESPHome.
This differs from Wake-on-LAN (WoL): ESPHome’s WoL button sends a network magic packet addressed using the target computer’s MAC address. The relay method operates the physical power-button circuit instead. It can be useful when WoL is not available or suitable, but it is not universally compatible and is not inherently more reliable.
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Choose a board that matches your setup
| Option | Form factor and documented I/O | Programming and PC-state sensing |
|---|---|---|
| Sinilink XY-WPCE PCIe computer remote | Dedicated PCIe device. Its guide maps GPIO5 to the simulated power press, GPIO10 to the case-button input and GPIO12 to a power-status signal. | The guide documents case-button input and power-state signaling, as well as an ESPHome configuration. Check the actual unit’s programming method and revision before buying or wiring. |
| ESP32 Relay x1 | Generic one-relay board; the documented ESP32-WROOM-32E example uses GPIO16 for relay control and has COM/NO/NC terminals. | Has a six-pin programming header. Its micro-USB port is for power, not serial flashing. The cited guide does not document a PC power-state signal. |
| ESP32 Relay x2 | Generic two-relay board; board-specific pinout and features apply. | Consult the device guide for the exact model’s programming notes and configuration before connecting it. |
These examples are specific device guides, not proof that every motherboard or board revision will work. Confirm the exact pinout, relay behavior, programming header and voltage requirements for your hardware. No reliable current seller price is established for these devices.
#1 Best Overall
- Relay supports Normally Open and Normally Closed
- Relay supports High-level Trigger or Low-Level Trigger selectable by a jumper
- Relay with Optocoupler Isolation
- Relay with Terminal Blocks for both Input and Output Interface
- Relay with two LED Indicators: power (green LED), the relay status (red LED)
Configure a momentary press, not a held signal
Set the relay to close briefly and then return to its inactive state. The XY-WPCE guide uses a 0.5-second pulse; ESPHome’s GPIO Switch documentation also shows a 500 ms momentary example. Many motherboards may interpret a press held for five seconds or longer as a forced shutdown, so do not leave the relay on as a persistent switch.
For a generic relay board, adapt the GPIO assignment to its documented pinout. The ESP32 Relay x1 example assigns GPIO16 to the relay; the XY-WPCE guide assigns GPIO5 to the simulated power press. Do not copy one board’s pin number to another without verifying its configuration.
Rank #2
- Original Songle Relay
- 30VDC 250VAC Load：The power switch is compatible with 10A 250VAC and 10A 30VDC load.
- Optocoupler Isolator:3V/3.3V power relay module supports photocoupler isolation control.
Flash and wire the hardware safely
- Identify the board and its programming method. Check the manufacturer or device guide for the board revision, programming header, required voltage and boot procedure. Some boards require a USB-to-serial adapter and jumper wires; the ESP32 Relay x1 board’s micro-USB connector supplies power rather than serial flashing.
- Flash ESPHome using the board’s documented procedure. ESPHome’s serial-flashing guide covers USB-to-serial connections and GPIO0 boot mode. Match the adapter’s voltage to the board: a 5 V supply connected to hardware expecting 3.3 V can destroy it.
- Connect only the relay’s low-voltage contacts to the PC power-switch header. Use the motherboard manual to identify the correct power-switch pins. This project concerns the PC’s low-voltage button circuit, not switching mains power. ESPHome warns: “Do not connect your device to mains electricity while following this guide.”
- Test the relay pulse before relying on remote control. Confirm that it closes only momentarily, releases as expected and does not interfere with the case button or other motherboard connections.
Prevent an unintended press during startup
Configure the relay output to start inactive, and include an on-boot action that turns it off. The XY-WPCE guide uses this approach to avoid triggering the power circuit during a restart or Wi-Fi loss.
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Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Clear out junk files and repair common Windows errorsFree Scan →A safe firmware default is not the whole story: ESPHome notes that a GPIO may have pull-ups active during reset, before ESPHome takes control. Check the board’s electrical behavior and test its startup and reset states with care before connecting it to the motherboard.
Quick Recap
Best Value
- AC-DC switching power supply module, output switch signals, the power supply mode supports AC220V/DC5-30V
- ESP32--32E WiFi module, large capacity 4M byte flash
- ESP32 32E WIFI relay module WiFi module RST reset button and a programmable button
- The I/O port of the WIFI module and the UART program download port are led out for secondary development
- ESP32 wireless WIFI 4 channel relay module WIFI module with 1 programmable LED and relay indicator onboard
Rank #4
- Direct ESP32-C3 Plug-and-Play Design: Seamlessly connects with ESP32-C3 development boards without complex wiring. Ideal for quick DIY setup of smart home automation and remote control projects. The onboard socket connects directly to the ESP32-C3's 5V, GND, GPIO5, and GPIO6 pins (power supply and dual-channel relay control signals).
- ESPHome & Home Assistant Ready: Fully compatible with ESPHome and Home Assistant platforms. Includes GitHub documentation and practical code examples for rapid integration into your smart home network.
- Versatile Power Options: Flexible power input via Type-C USB port or 5V screw terminal block, allowing reliable power delivery based on your specific setup needs.
- 4 Flexible Operating Modes: Supports Type-C power, 5V terminal power, standalone PH2.0-4Pin connection to external microcontrollers, and pin expansion for attaching extra sensors alongside the ESP32-C3.
- Reliable Low-Level Trigger: Features 2-channel low-level trigger relays for accurate and stable signal control, suitable for switching household appliances and low-voltage circuits.
Rank #3
- Programmable Relay Module 8 Channel with ESP32 BLE Development Board for Smart Home Control Secondary Development Projects DC5-30V
- The on board ESP32-32E module with large capacity 4M Byte Flash, supports the use of development tools and provide reference programs in the development environment.
- On board 8 circuit 5V relay, output switch , suitable for controlling loads with working voltage within AC 250V and DC 30V.
- The I/O ports and UART program download ports of the ESP32 module are all exported, making it convenient for secondary development.
- On board ESP32 module programmable buttons and reset buttons, on board 1 programmable LED and relay indicator light.
What to verify before choosing this approach
- The motherboard exposes an identifiable power-switch header, and the chosen relay can be safely connected across the correct contacts.
- The board’s GPIO mapping, relay terminals, programming method and voltage match the exact hardware revision.
- The firmware generates a short pulse and leaves the relay inactive on boot.
- You have considered whether WoL is a better fit: it sends a magic packet over the network, while the relay physically imitates the case button.
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