diff --git a/lib/SteelSeriesNova5.psm1 b/lib/SteelSeriesNova5.psm1
new file mode 100644
index 0000000..f407eb2
--- /dev/null
+++ b/lib/SteelSeriesNova5.psm1
@@ -0,0 +1,396 @@
+#requires -Version 5.1
+# SteelSeriesNova5.psm1 - physical ON/OFF detection for Arctis Nova 5/5X.
+#
+# Protocol reference (reverse engineered by HeadsetControl):
+#   VID 0x1038
+#   PID 0x2232 (Nova 5), 0x2253 (Nova 5X)
+#   HID UsagePage 0xFFC0, Usage 0x0001
+#   status request: 00 B0
+#   response byte[1] == 0x02 => headset offline
+#
+# No SteelSeries GG or third-party DLL is required. The C# helper uses the
+# Windows HID/SetupAPI APIs already present in the operating system.
+
+Set-StrictMode -Version Latest
+
+function Resolve-SteelSeriesNova5Status {
+    [CmdletBinding()]
+    param(
+        [Parameter(Mandatory = $true)]
+        [AllowEmptyCollection()]
+        [byte[]]$Data
+    )
+
+    # HeadsetControl rejects responses shorter than 16 bytes. Do the same:
+    # a malformed/partial response is Unknown, never interpreted as OFF.
+    if ($null -eq $Data -or $Data.Length -lt 16) {
+        return 'Unknown'
+    }
+
+    if ($Data[1] -eq 0x02) {
+        return 'Disconnected'
+    }
+
+    return 'Connected'
+}
+
+function Initialize-SteelSeriesNova5Hid {
+    if ('AutoSwitch.SteelSeriesNova5Hid' -as [type]) {
+        return
+    }
+
+    Add-Type -TypeDefinition @'
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Runtime.InteropServices;
+using Microsoft.Win32.SafeHandles;
+
+namespace AutoSwitch
+{
+    public static class SteelSeriesNova5Hid
+    {
+        private const ushort VID_STEELSERIES = 0x1038;
+        private const ushort PID_NOVA5 = 0x2232;
+        private const ushort PID_NOVA5X = 0x2253;
+        private const ushort USAGE_PAGE = 0xFFC0;
+        private const ushort USAGE = 0x0001;
+
+        private const uint DIGCF_PRESENT = 0x00000002;
+        private const uint DIGCF_DEVICEINTERFACE = 0x00000010;
+        private const uint GENERIC_READ = 0x80000000;
+        private const uint GENERIC_WRITE = 0x40000000;
+        private const uint FILE_SHARE_READ = 0x00000001;
+        private const uint FILE_SHARE_WRITE = 0x00000002;
+        private const uint OPEN_EXISTING = 3;
+        private const uint FILE_FLAG_OVERLAPPED = 0x40000000;
+        private static readonly IntPtr INVALID_HANDLE_VALUE = new IntPtr(-1);
+
+        [StructLayout(LayoutKind.Sequential)]
+        private struct SP_DEVICE_INTERFACE_DATA
+        {
+            public int cbSize;
+            public Guid InterfaceClassGuid;
+            public int Flags;
+            public IntPtr Reserved;
+        }
+
+        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
+        private struct SP_DEVICE_INTERFACE_DETAIL_DATA
+        {
+            public int cbSize;
+
+            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 512)]
+            public string DevicePath;
+        }
+
+        [StructLayout(LayoutKind.Sequential)]
+        private struct HIDD_ATTRIBUTES
+        {
+            public int Size;
+            public ushort VendorID;
+            public ushort ProductID;
+            public ushort VersionNumber;
+        }
+
+        [StructLayout(LayoutKind.Sequential)]
+        private struct HIDP_CAPS
+        {
+            public ushort Usage;
+            public ushort UsagePage;
+            public ushort InputReportByteLength;
+            public ushort OutputReportByteLength;
+            public ushort FeatureReportByteLength;
+
+            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 17)]
+            public ushort[] Reserved;
+
+            public ushort NumberLinkCollectionNodes;
+            public ushort NumberInputButtonCaps;
+            public ushort NumberInputValueCaps;
+            public ushort NumberInputDataIndices;
+            public ushort NumberOutputButtonCaps;
+            public ushort NumberOutputValueCaps;
+            public ushort NumberOutputDataIndices;
+            public ushort NumberFeatureButtonCaps;
+            public ushort NumberFeatureValueCaps;
+            public ushort NumberFeatureDataIndices;
+        }
+
+        [DllImport("hid.dll")]
+        private static extern void HidD_GetHidGuid(out Guid HidGuid);
+
+        [DllImport("hid.dll", SetLastError = true)]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        private static extern bool HidD_GetAttributes(SafeFileHandle HidDeviceObject, ref HIDD_ATTRIBUTES Attributes);
+
+        [DllImport("hid.dll", SetLastError = true)]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        private static extern bool HidD_GetPreparsedData(SafeFileHandle HidDeviceObject, out IntPtr PreparsedData);
+
+        [DllImport("hid.dll", SetLastError = true)]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        private static extern bool HidD_FreePreparsedData(IntPtr PreparsedData);
+
+        [DllImport("hid.dll")]
+        private static extern int HidP_GetCaps(IntPtr PreparsedData, out HIDP_CAPS Capabilities);
+
+        [DllImport("setupapi.dll", SetLastError = true)]
+        private static extern IntPtr SetupDiGetClassDevs(
+            ref Guid ClassGuid,
+            IntPtr Enumerator,
+            IntPtr hwndParent,
+            uint Flags);
+
+        [DllImport("setupapi.dll", SetLastError = true)]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        private static extern bool SetupDiEnumDeviceInterfaces(
+            IntPtr DeviceInfoSet,
+            IntPtr DeviceInfoData,
+            ref Guid InterfaceClassGuid,
+            uint MemberIndex,
+            ref SP_DEVICE_INTERFACE_DATA DeviceInterfaceData);
+
+        [DllImport("setupapi.dll", CharSet = CharSet.Unicode, SetLastError = true)]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        private static extern bool SetupDiGetDeviceInterfaceDetail(
+            IntPtr DeviceInfoSet,
+            ref SP_DEVICE_INTERFACE_DATA DeviceInterfaceData,
+            ref SP_DEVICE_INTERFACE_DETAIL_DATA DeviceInterfaceDetailData,
+            uint DeviceInterfaceDetailDataSize,
+            out uint RequiredSize,
+            IntPtr DeviceInfoData);
+
+        [DllImport("setupapi.dll")]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        private static extern bool SetupDiDestroyDeviceInfoList(IntPtr DeviceInfoSet);
+
+        [DllImport("kernel32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
+        private static extern SafeFileHandle CreateFile(
+            string lpFileName,
+            uint dwDesiredAccess,
+            uint dwShareMode,
+            IntPtr lpSecurityAttributes,
+            uint dwCreationDisposition,
+            uint dwFlagsAndAttributes,
+            IntPtr hTemplateFile);
+
+        private sealed class Candidate : IDisposable
+        {
+            public SafeFileHandle Handle;
+            public HIDP_CAPS Caps;
+
+            public void Dispose()
+            {
+                if (Handle != null && !Handle.IsInvalid)
+                    Handle.Dispose();
+            }
+        }
+
+        private static bool IsSupportedPid(ushort pid)
+        {
+            return pid == PID_NOVA5 || pid == PID_NOVA5X;
+        }
+
+        private static Candidate OpenReceiver()
+        {
+            Guid hidGuid;
+            HidD_GetHidGuid(out hidGuid);
+
+            IntPtr set = SetupDiGetClassDevs(
+                ref hidGuid,
+                IntPtr.Zero,
+                IntPtr.Zero,
+                DIGCF_PRESENT | DIGCF_DEVICEINTERFACE);
+
+            if (set == INVALID_HANDLE_VALUE)
+                return null;
+
+            try
+            {
+                for (uint index = 0; ; index++)
+                {
+                    SP_DEVICE_INTERFACE_DATA iface = new SP_DEVICE_INTERFACE_DATA();
+                    iface.cbSize = Marshal.SizeOf(typeof(SP_DEVICE_INTERFACE_DATA));
+
+                    if (!SetupDiEnumDeviceInterfaces(set, IntPtr.Zero, ref hidGuid, index, ref iface))
+                        break;
+
+                    SP_DEVICE_INTERFACE_DETAIL_DATA detail = new SP_DEVICE_INTERFACE_DETAIL_DATA();
+                    detail.cbSize = IntPtr.Size == 8 ? 8 : 6;
+
+                    uint required;
+                    uint detailSize = (uint)Marshal.SizeOf(typeof(SP_DEVICE_INTERFACE_DETAIL_DATA));
+                    if (!SetupDiGetDeviceInterfaceDetail(set, ref iface, ref detail, detailSize, out required, IntPtr.Zero))
+                        continue;
+
+                    SafeFileHandle handle = CreateFile(
+                        detail.DevicePath,
+                        GENERIC_READ | GENERIC_WRITE,
+                        FILE_SHARE_READ | FILE_SHARE_WRITE,
+                        IntPtr.Zero,
+                        OPEN_EXISTING,
+                        FILE_FLAG_OVERLAPPED,
+                        IntPtr.Zero);
+
+                    if (handle == null || handle.IsInvalid)
+                    {
+                        if (handle != null) handle.Dispose();
+                        continue;
+                    }
+
+                    HIDD_ATTRIBUTES attrs = new HIDD_ATTRIBUTES();
+                    attrs.Size = Marshal.SizeOf(typeof(HIDD_ATTRIBUTES));
+                    if (!HidD_GetAttributes(handle, ref attrs) ||
+                        attrs.VendorID != VID_STEELSERIES ||
+                        !IsSupportedPid(attrs.ProductID))
+                    {
+                        handle.Dispose();
+                        continue;
+                    }
+
+                    IntPtr preparsed = IntPtr.Zero;
+                    try
+                    {
+                        if (!HidD_GetPreparsedData(handle, out preparsed) || preparsed == IntPtr.Zero)
+                        {
+                            handle.Dispose();
+                            continue;
+                        }
+
+                        HIDP_CAPS caps;
+                        // HIDP_STATUS_SUCCESS == 0x00110000.
+                        if (HidP_GetCaps(preparsed, out caps) != 0x00110000 ||
+                            caps.UsagePage != USAGE_PAGE || caps.Usage != USAGE)
+                        {
+                            handle.Dispose();
+                            continue;
+                        }
+
+                        Candidate candidate = new Candidate();
+                        candidate.Handle = handle;
+                        candidate.Caps = caps;
+                        return candidate;
+                    }
+                    finally
+                    {
+                        if (preparsed != IntPtr.Zero)
+                            HidD_FreePreparsedData(preparsed);
+                    }
+                }
+            }
+            finally
+            {
+                SetupDiDestroyDeviceInfoList(set);
+            }
+
+            return null;
+        }
+
+        public static bool ReceiverPresent()
+        {
+            using (Candidate receiver = OpenReceiver())
+            {
+                return receiver != null;
+            }
+        }
+
+        private static bool WaitAndComplete(IAsyncResult asyncResult, int timeoutMs, Action<IAsyncResult> complete)
+        {
+            if (!asyncResult.AsyncWaitHandle.WaitOne(timeoutMs))
+                return false;
+
+            complete(asyncResult);
+            return true;
+        }
+
+        // Returns the raw HID status response, or null when the receiver cannot
+        // be queried safely. Callers must treat null as Unknown, never as OFF.
+        public static byte[] QueryStatus(int timeoutMs)
+        {
+            if (timeoutMs < 100) timeoutMs = 100;
+
+            using (Candidate receiver = OpenReceiver())
+            {
+                if (receiver == null)
+                    return null;
+
+                int outputLength = Math.Max(2, (int)receiver.Caps.OutputReportByteLength);
+                int inputLength = Math.Max(128, (int)receiver.Caps.InputReportByteLength);
+
+                byte[] request = new byte[outputLength];
+                request[0] = 0x00; // report ID
+                request[1] = 0xB0; // SteelSeries Nova status request
+
+                byte[] response = new byte[inputLength];
+
+                try
+                {
+                    using (FileStream stream = new FileStream(receiver.Handle, FileAccess.ReadWrite, 4096, true))
+                    {
+                        // Ownership moves to FileStream; prevent Candidate from
+                        // closing the handle twice.
+                        receiver.Handle = null;
+
+                        IAsyncResult write = stream.BeginWrite(request, 0, request.Length, null, null);
+                        if (!WaitAndComplete(write, timeoutMs, stream.EndWrite))
+                            return null;
+
+                        IAsyncResult read = stream.BeginRead(response, 0, response.Length, null, null);
+                        int count = -1;
+                        if (!read.AsyncWaitHandle.WaitOne(timeoutMs))
+                            return null;
+                        count = stream.EndRead(read);
+
+                        if (count <= 0)
+                            return null;
+
+                        byte[] exact = new byte[count];
+                        Buffer.BlockCopy(response, 0, exact, 0, count);
+                        return exact;
+                    }
+                }
+                catch
+                {
+                    return null;
+                }
+            }
+        }
+    }
+}
+'@ -ErrorAction Stop
+}
+
+function Test-SteelSeriesNova5Receiver {
+    [CmdletBinding()]
+    param()
+
+    try {
+        Initialize-SteelSeriesNova5Hid
+        return [AutoSwitch.SteelSeriesNova5Hid]::ReceiverPresent()
+    }
+    catch {
+        return $false
+    }
+}
+
+function Get-SteelSeriesNova5State {
+    [CmdletBinding()]
+    param(
+        [int]$TimeoutMilliseconds = 800
+    )
+
+    try {
+        Initialize-SteelSeriesNova5Hid
+        $data = [AutoSwitch.SteelSeriesNova5Hid]::QueryStatus($TimeoutMilliseconds)
+        if ($null -eq $data) {
+            return 'Unknown'
+        }
+        return Resolve-SteelSeriesNova5Status -Data $data
+    }
+    catch {
+        return 'Unknown'
+    }
+}
+
+Export-ModuleMember -Function Resolve-SteelSeriesNova5Status, Test-SteelSeriesNova5Receiver, Get-SteelSeriesNova5State
diff --git a/tests/SteelSeriesNova5.Tests.ps1 b/tests/SteelSeriesNova5.Tests.ps1
new file mode 100644
index 0000000..674d15f
--- /dev/null
+++ b/tests/SteelSeriesNova5.Tests.ps1
@@ -0,0 +1,23 @@
+#requires -Version 5.1
+
+$module = Join-Path $PSScriptRoot '..\lib\SteelSeriesNova5.psm1'
+Import-Module $module -Force
+
+Describe 'SteelSeries Arctis Nova 5 HID status mapping' {
+    It 'maps the documented offline marker to Disconnected' {
+        $data = New-Object byte[] 16
+        $data[1] = 0x02
+        Resolve-SteelSeriesNova5Status -Data $data | Should -Be 'Disconnected'
+    }
+
+    It 'maps a normal status response to Connected' {
+        $data = New-Object byte[] 16
+        $data[1] = 0x00
+        Resolve-SteelSeriesNova5Status -Data $data | Should -Be 'Connected'
+    }
+
+    It 'treats a short response as Unknown' {
+        $data = New-Object byte[] 8
+        Resolve-SteelSeriesNova5Status -Data $data | Should -Be 'Unknown'
+    }
+}
diff --git a/tools/Test-SteelSeriesNova5Hid.ps1 b/tools/Test-SteelSeriesNova5Hid.ps1
new file mode 100644
index 0000000..294b367
--- /dev/null
+++ b/tools/Test-SteelSeriesNova5Hid.ps1
@@ -0,0 +1,32 @@
+#requires -Version 5.1
+$ErrorActionPreference = 'Stop'
+
+$module = Join-Path (Split-Path -Parent $PSScriptRoot) 'lib\SteelSeriesNova5.psm1'
+Import-Module $module -Force
+
+Write-Host 'SteelSeries Arctis Nova 5/5X HID diagnostic' -ForegroundColor Cyan
+Write-Host ''
+
+if (-not (Test-SteelSeriesNova5Receiver)) {
+    Write-Host 'No compatible Nova 5/5X receiver was found.' -ForegroundColor Red
+    exit 2
+}
+
+Write-Host 'Compatible receiver found.' -ForegroundColor Green
+Write-Host 'Press Ctrl+C to stop. Turn the headset ON and OFF and watch the state.' -ForegroundColor DarkGray
+Write-Host ''
+
+$last = $null
+while ($true) {
+    $state = Get-SteelSeriesNova5State -TimeoutMilliseconds 800
+    if ($state -ne $last) {
+        $color = switch ($state) {
+            'Connected'    { 'Green' }
+            'Disconnected' { 'Yellow' }
+            default        { 'Red' }
+        }
+        Write-Host ('[{0}] {1}' -f (Get-Date -Format 'HH:mm:ss.fff'), $state) -ForegroundColor $color
+        $last = $state
+    }
+    Start-Sleep -Milliseconds 500
+}