Adjust Checksum Offload in Windows Registry

Hardware checksum offloading transfers the task of computing and verifying packet checksums from the CPU to the Network Interface Card (NIC) to improve system performance. In Windows, while these settings can be configured through the Device Manager, advanced users and administrators can directly modify the network adapter parameters using the Windows Registry Editor (regedit). This guide outlines the exact registry paths, key names, and values required to enable or disable IPv4 and IPv6 checksum offloading for your network adapter.

Step 1: Open the Registry Editor

1. Press Windows Key + R to open the Run dialog.
2. Type regedit and press Enter.
3. If prompted by User Account Control (UAC), click Yes.

Step 2: Navigate to the Network Adapters Registry Key

In the Registry Editor address bar, paste the following path and press Enter:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4d36e972-e325-11ce-bfc1-08002be10318}

This GUID contains subkeys named numerically (e.g., 0000, 0001, 0002), each representing a physical or virtual network interface installed on your system.

Step 3: Identify Your Network Adapter

1. Click through the numbered folders (0000, 0001, etc.).
2. In the right pane, look at the DriverDesc string value.
3. Locate the folder where DriverDesc matches the name of your physical network adapter (e.g., Intel(R) Ethernet Connection or Realtek PCIe GbE Family Controller).

Step 4: Modify Checksum Offload Parameters

Within your adapter’s folder, locate or create the relevant String Value (REG_SZ) or DWORD (32-bit) Value corresponding to the checksum functions you want to modify:

• *IPChecksumOffloadIPv4 – IPv4 Header Checksum Offload
• *TCPChecksumOffloadIPv4 – TCP Checksum Offload (IPv4)
• *TCPChecksumOffloadIPv6 – TCP Checksum Offload (IPv6)
• *UDPChecksumOffloadIPv4 – UDP Checksum Offload (IPv4)
• *UDPChecksumOffloadIPv6 – UDP Checksum Offload (IPv6)

Value Definitions:

Double-click the parameter you want to change and set its value:

• 0 = Disabled (Checksum verification handled by the CPU)
• 1 = TX Enabled (Transmit only)
• 2 = RX Enabled (Receive only)
• 3 = RX & TX Enabled (Hardware handles both transmit and receive checksums)

(Note: If a specific key does not exist and you wish to apply the setting, right-click an empty space in the right pane, select New > String Value, name it with the exact parameter name including the asterisk *, and assign the desired value.)

Step 5: Apply the Changes

Registry modifications for hardware offloading take effect after restarting the network adapter or rebooting the computer.

To restart the adapter without rebooting: 1. Press Windows Key + X and select Network Connections. 2. Click Change adapter options. 3. Right-click your network adapter, select Disable, wait a few seconds, then right-click and select Enable.