diff --git a/Source/Core/Core/BootManager.cpp b/Source/Core/Core/BootManager.cpp
index 8d9a305c29..bfea949301 100644
--- a/Source/Core/Core/BootManager.cpp
+++ b/Source/Core/Core/BootManager.cpp
@@ -55,10 +55,24 @@ struct ConfigCache
 	unsigned int framelimit, frameSkip;
 	TEXIDevices m_EXIDevice[MAX_EXI_CHANNELS];
 	std::string strBackend, sBackend;
+	std::string m_strGPUDeterminismMode;
 	bool bSetFramelimit, bSetEXIDevice[MAX_EXI_CHANNELS], bSetVolume, bSetPads[MAX_SI_CHANNELS], bSetWiimoteSource[MAX_BBMOTES], bSetFrameSkip;
 };
 static ConfigCache config_cache;
 
+static GPUDeterminismMode ParseGPUDeterminismMode(const std::string& mode)
+{
+	if (mode == "auto")
+		return GPU_DETERMINISM_AUTO;
+	if (mode == "none")
+		return GPU_DETERMINISM_NONE;
+	if (mode == "fake-completion")
+		return GPU_DETERMINISM_FAKE_COMPLETION;
+
+	NOTICE_LOG(BOOT, "Unknown GPU determinism mode %s", mode.c_str());
+	return GPU_DETERMINISM_AUTO;
+}
+
 // Boot the ISO or file
 bool BootCore(const std::string& _rFilename)
 {
@@ -109,6 +123,7 @@ bool BootCore(const std::string& _rFilename)
 		config_cache.bMergeBlocks = StartUp.bMergeBlocks;
 		config_cache.bDSPHLE = StartUp.bDSPHLE;
 		config_cache.strBackend = StartUp.m_strVideoBackend;
+		config_cache.m_strGPUDeterminismMode = StartUp.m_strGPUDeterminismMode;
 		config_cache.m_EnableJIT = SConfig::GetInstance().m_DSPEnableJIT;
 		config_cache.bDSPThread = StartUp.bDSPThread;
 		config_cache.Volume = SConfig::GetInstance().m_Volume;
@@ -168,6 +183,8 @@ bool BootCore(const std::string& _rFilename)
 		dsp_section->Get("EnableJIT",         &SConfig::GetInstance().m_DSPEnableJIT, SConfig::GetInstance().m_DSPEnableJIT);
 		dsp_section->Get("Backend",           &SConfig::GetInstance().sBackend, SConfig::GetInstance().sBackend);
 		VideoBackend::ActivateBackend(StartUp.m_strVideoBackend);
+		core_section->Get("GPUDeterminismMode", &StartUp.m_strGPUDeterminismMode, StartUp.m_strGPUDeterminismMode);
+		StartUp.m_GPUDeterminismMode = ParseGPUDeterminismMode(StartUp.m_strGPUDeterminismMode);
 
 		for (unsigned int i = 0; i < MAX_SI_CHANNELS; ++i)
 		{
@@ -277,6 +294,7 @@ void Stop()
 		StartUp.bDSPHLE = config_cache.bDSPHLE;
 		StartUp.bDSPThread = config_cache.bDSPThread;
 		StartUp.m_strVideoBackend = config_cache.strBackend;
+		StartUp.m_strGPUDeterminismMode = config_cache.m_strGPUDeterminismMode;
 		VideoBackend::ActivateBackend(StartUp.m_strVideoBackend);
 		StartUp.bHLE_BS2 = config_cache.bHLE_BS2;
 		SConfig::GetInstance().sBackend = config_cache.sBackend;
diff --git a/Source/Core/Core/ConfigManager.cpp b/Source/Core/Core/ConfigManager.cpp
index 5b672305ed..3942fd87c9 100644
--- a/Source/Core/Core/ConfigManager.cpp
+++ b/Source/Core/Core/ConfigManager.cpp
@@ -317,6 +317,7 @@ void SConfig::SaveCoreSettings(IniFile& ini)
 	core->Set("FrameLimit", m_Framelimit);
 	core->Set("FrameSkip", m_FrameSkip);
 	core->Set("GFXBackend", m_LocalCoreStartupParameter.m_strVideoBackend);
+	core->Set("GPUDeterminismMode", m_LocalCoreStartupParameter.m_strGPUDeterminismMode);
 }
 
 void SConfig::SaveMovieSettings(IniFile& ini)
@@ -542,6 +543,7 @@ void SConfig::LoadCoreSettings(IniFile& ini)
 	core->Get("FrameLimit",                &m_Framelimit,                                  1); // auto frame limit by default
 	core->Get("FrameSkip",                 &m_FrameSkip,                                   0);
 	core->Get("GFXBackend",                &m_LocalCoreStartupParameter.m_strVideoBackend, "");
+	core->Get("GPUDeterminismMode",        &m_LocalCoreStartupParameter.m_strGPUDeterminismMode, "auto");
 }
 
 void SConfig::LoadMovieSettings(IniFile& ini)
diff --git a/Source/Core/Core/CoreParameter.h b/Source/Core/Core/CoreParameter.h
index b6008b3145..898c949714 100644
--- a/Source/Core/Core/CoreParameter.h
+++ b/Source/Core/Core/CoreParameter.h
@@ -97,6 +97,15 @@ enum Hotkey
 	NUM_HOTKEYS,
 };
 
+enum GPUDeterminismMode
+{
+	GPU_DETERMINISM_AUTO,
+	GPU_DETERMINISM_NONE,
+	// This is currently the only mode.  There will probably be at least
+	// one more at some point.
+	GPU_DETERMINISM_FAKE_COMPLETION,
+};
+
 struct SCoreStartupParameter
 {
 	// Settings
@@ -200,6 +209,10 @@ struct SCoreStartupParameter
 	EBootType m_BootType;
 
 	std::string m_strVideoBackend;
+	std::string m_strGPUDeterminismMode;
+
+	// set based on the string version
+	GPUDeterminismMode m_GPUDeterminismMode;
 
 	// files
 	std::string m_strFilename;
diff --git a/Source/Core/VideoCommon/Fifo.cpp b/Source/Core/VideoCommon/Fifo.cpp
index a47438c41e..44322d4d3b 100644
--- a/Source/Core/VideoCommon/Fifo.cpp
+++ b/Source/Core/VideoCommon/Fifo.cpp
@@ -421,21 +421,40 @@ void Fifo_UpdateWantDeterminism(bool want)
 {
 	// We are paused (or not running at all yet) and have m_csHWVidOccupied, so
 	// it should be safe to change this.
-	g_use_deterministic_gpu_thread = want && SConfig::GetInstance().m_LocalCoreStartupParameter.bCPUThread;
-
-	// Hack: For now movies are an exception to this being on (but not
-	// to wanting determinism in general).  Once vertex arrays are
-	// fixed, there should be no reason to want this off for movies by
-	// default, so this can be removed.
-	if (NetPlay::IsNetPlayRunning())
-		g_use_deterministic_gpu_thread = false;
-
-	if (g_use_deterministic_gpu_thread)
+	const SCoreStartupParameter& param = SConfig::GetInstance().m_LocalCoreStartupParameter;
+	bool gpu_thread;
+	switch (param.m_GPUDeterminismMode)
 	{
-		// These haven't been updated in non-deterministic mode.
-		s_video_buffer_seen_ptr = g_video_buffer_pp_read_ptr = g_video_buffer_read_ptr;
-		CopyPreprocessCPStateFromMain();
-		VertexLoaderManager::MarkAllDirty();
+		case GPU_DETERMINISM_AUTO:
+			gpu_thread = want;
+
+			// Hack: For now movies are an exception to this being on (but not
+			// to wanting determinism in general).  Once vertex arrays are
+			// fixed, there should be no reason to want this off for movies by
+			// default, so this can be removed.
+			if (!NetPlay::IsNetPlayRunning())
+				gpu_thread = false;
+
+			break;
+		case GPU_DETERMINISM_NONE:
+			gpu_thread = false;
+			break;
+		case GPU_DETERMINISM_FAKE_COMPLETION:
+			gpu_thread = true;
+			break;
 	}
 
+	gpu_thread = gpu_thread && SConfig::GetInstance().m_LocalCoreStartupParameter.bCPUThread;
+
+	if (g_use_deterministic_gpu_thread != gpu_thread)
+	{
+		g_use_deterministic_gpu_thread = gpu_thread;
+		if (gpu_thread)
+		{
+			// These haven't been updated in non-deterministic mode.
+			s_video_buffer_seen_ptr = g_video_buffer_pp_read_ptr = g_video_buffer_read_ptr;
+			CopyPreprocessCPStateFromMain();
+			VertexLoaderManager::MarkAllDirty();
+		}
+	}
 }