Add GPU detection and usage retrieval with error handling

NvmlWrapper.cs

@@ -9,6 +9,15 @@ public static class NvmlWrapper
     [DllImport("nvml.dll", EntryPoint = "nvmlShutdown")]
     public static extern int NvmlShutdown();
 
+    // Get device count
+    [DllImport("nvml.dll", CallingConvention = CallingConvention.Cdecl)]
+    private static extern int nvmlDeviceGetCount_v2(ref uint deviceCount);
+
+    public static int NvmlDeviceGetCount(ref uint deviceCount)
+    {
+        return nvmlDeviceGetCount_v2(ref deviceCount);
+    }
+
     [DllImport("nvml.dll", EntryPoint = "nvmlDeviceGetHandleByIndex_v2")]
     public static extern int NvmlDeviceGetHandleByIndex(int index, out IntPtr device);
 

Worker.cs

@@ -190,6 +190,21 @@ namespace ResourceMonitorService
 
         private object GetGpuUsage()
         {
+            if (!IsNvidiaGpuPresent())
+            {
+                return new
+                {
+                    Usage = 0,
+                    Temperature = 0,
+                    FanSpeed = 0,
+                    IsAvailable = false,
+                    Message = "No NVIDIA GPU detected"
+                };
+            }
+
+            try
+            {
+
                 NvmlWrapper.NvmlInit();
                 IntPtr device;
                 NvmlWrapper.NvmlDeviceGetHandleByIndex(0, out device);
@@ -211,6 +226,48 @@ namespace ResourceMonitorService
                     FanSpeed = fanSpeed
                 };
             }
+            catch (Exception ex)
+            {
+                return new
+                {
+                    Usage = 0,
+                    Temperature = 0,
+                    FanSpeed = 0,
+                    IsAvailable = false,
+                    Error = ex.Message
+                };
+            }
+        }
+
+        private bool IsNvidiaGpuPresent()
+        {
+            try
+            {
+                // Method 1: Try to initialize NVML
+                NvmlWrapper.NvmlInit();
+                uint deviceCount = 0;
+                NvmlWrapper.NvmlDeviceGetCount(ref deviceCount);
+                NvmlWrapper.NvmlShutdown();
+
+                return deviceCount > 0;
+            }
+            catch
+            {
+                // Method 2: Fallback to checking using WMI
+                try
+                {
+                    using (var searcher = new ManagementObjectSearcher("SELECT * FROM Win32_VideoController WHERE Name LIKE '%NVIDIA%'"))
+                    {
+                        var collection = searcher.Get();
+                        return collection.Count > 0;
+                    }
+                }
+                catch
+                {
+                    return false;
+                }
+            }
+        }
 
         private object GetCurrentlyRunningGame()
         {