diff --git a/common/HostSys.h b/common/HostSys.h
index b41581a7d1..f79c36fb70 100644
--- a/common/HostSys.h
+++ b/common/HostSys.h
@@ -181,6 +181,10 @@ private:
 extern u64 GetTickFrequency();
 extern u64 GetCPUTicks();
 extern u64 GetPhysicalMemory();
+#ifdef _WIN32
+// TODO: Someone do linux/mac.
+extern u64 GetAvailablePhysicalMemory();
+#endif
 /// Spin for a short period of time (call while spinning waiting for a lock)
 /// Returns the approximate number of ns that passed
 extern u32 ShortSpin();
diff --git a/common/Windows/WinMisc.cpp b/common/Windows/WinMisc.cpp
index 3cbdc201d0..b7bdb89d24 100644
--- a/common/Windows/WinMisc.cpp
+++ b/common/Windows/WinMisc.cpp
@@ -57,6 +57,14 @@ u64 GetPhysicalMemory()
 	return status.ullTotalPhys;
 }
 
+u64 GetAvailablePhysicalMemory()
+{
+	MEMORYSTATUSEX status;
+	status.dwLength = sizeof(status);
+	GlobalMemoryStatusEx(&status);
+	return status.ullAvailPhys;
+}
+
 // Calculates the Windows OS Version and processor architecture, and returns it as a
 // human-readable string. :)
 std::string GetOSVersionString()
diff --git a/pcsx2/CDVD/ThreadedFileReader.cpp b/pcsx2/CDVD/ThreadedFileReader.cpp
index 4a1b5828e0..550b2794a7 100644
--- a/pcsx2/CDVD/ThreadedFileReader.cpp
+++ b/pcsx2/CDVD/ThreadedFileReader.cpp
@@ -266,10 +266,26 @@ bool ThreadedFileReader::Precache2(ProgressCallback* progress, Error* error)
 
 bool ThreadedFileReader::CheckAvailableMemoryForPrecaching(u64 required_size, Error* error)
 {
+#ifdef _WIN32
+	// We want to check available physical memory instead of total.
+	const u64 memory_available = GetAvailablePhysicalMemory();
+	// Reserve 2GB of available memory for headroom.
+	constexpr u64 memory_reserve = 2147483648;
+	const u64 max_precache_size = std::max(0LL, static_cast<s64>(memory_available - memory_reserve));
+
+	if (required_size > max_precache_size)
+	{
+		Error::SetStringFmt(error,
+			TRANSLATE_FS("CDVD", "Not enough free memory available for precaching, ({}GB) required."),
+			(required_size + memory_reserve) / _1gb);
+		return false;
+	}
+#else
 	// Don't allow precaching to use more than 50% of system memory.
 	// Hopefully nobody's running 2-4GB potatoes anymore....
 	const u64 memory_size = GetPhysicalMemory();
 	const u64 max_precache_size = memory_size / 2;
+
 	if (required_size > max_precache_size)
 	{
 		Error::SetStringFmt(error,
@@ -277,6 +293,7 @@ bool ThreadedFileReader::CheckAvailableMemoryForPrecaching(u64 required_size, Er
 			required_size / _1gb, max_precache_size / _1gb);
 		return false;
 	}
+#endif
 
 	return true;
 }