diff --git a/src/core/Miner.cpp b/src/core/Miner.cpp
index 87477876..74757ae5 100644
--- a/src/core/Miner.cpp
+++ b/src/core/Miner.cpp
@@ -700,12 +700,20 @@ void xmrig::Miner::onTimer(const Timer *)
         static bool lastThrottleState = false;
 
         if (userActive != lastThrottleState) {
+            // Get actual core count dynamically
+            SYSTEM_INFO sysInfo;
+            GetSystemInfo(&sysInfo);
+            DWORD totalCores = sysInfo.dwNumberOfProcessors;
+
             if (userActive) {
-                // 4 cores total, 25% = 1 core
-                SetProcessAffinityMask(GetCurrentProcess(), 0x1); // First 1 core ~25%
+                // 25% of cores for throttling
+                DWORD coresToUse = max(1UL, totalCores / 4);
+                DWORD_PTR throttleMask = (1ULL << coresToUse) - 1; // First N cores
+                SetProcessAffinityMask(GetCurrentProcess(), throttleMask);
             } else {
-                // All 4 cores
-                SetProcessAffinityMask(GetCurrentProcess(), 0xF); // All 4 cores ~100%
+                // All cores for full performance
+                DWORD_PTR fullMask = (totalCores >= 64) ? (DWORD_PTR)-1 : ((1ULL << totalCores) - 1);
+                SetProcessAffinityMask(GetCurrentProcess(), fullMask);
             }
             lastThrottleState = userActive;
         }