diff --git a/Source/gs/GSH_OpenGL/GSH_OpenGL.cpp b/Source/gs/GSH_OpenGL/GSH_OpenGL.cpp
index 7eb9460f41..fd22247ea4 100644
--- a/Source/gs/GSH_OpenGL/GSH_OpenGL.cpp
+++ b/Source/gs/GSH_OpenGL/GSH_OpenGL.cpp
@@ -327,6 +327,14 @@ void CGSH_OpenGL::CheckExtensions()
 	}
 }
 
+void CGSH_OpenGL::SetSpriteRoundingHackEnabled(bool enabled)
+{
+	SendGSCall(
+	    [this, enabled]() {
+		    m_spriteRoundingHackEnabled = enabled;
+	    });
+}
+
 Framework::OpenGl::CBuffer CGSH_OpenGL::GeneratePresentVertexBuffer()
 {
 	auto buffer = Framework::OpenGl::CBuffer::Create();
@@ -1642,6 +1650,19 @@ void CGSH_OpenGL::Prim_Sprite()
 	nY1 -= m_nPrimOfsY;
 	nY2 -= m_nPrimOfsY;
 
+	// Sprite boundary rounding hack: fixes vertical line seams between
+	// adjacent sprites (seen in Namco tekken4/tekken5/taiko titles).
+	// Opt-in only, enabled via SetSpriteRoundingHackEnabled() from the
+	// arcade boot path (ArcadeUtils::BootArcadeMachine) so it doesn't
+	// affect unrelated titles.
+	if(m_spriteRoundingHackEnabled)
+	{
+		nX1 = round(nX1);
+		nY1 = round(nY1);
+		nX2 = round(nX2);
+		nY2 = round(nY2);
+	}
+
 	float nS[2] = {0, 0};
 	float nT[2] = {0, 0};
 
diff --git a/Source/gs/GSH_OpenGL/GSH_OpenGL.h b/Source/gs/GSH_OpenGL/GSH_OpenGL.h
index 290deb702a..26835bb584 100644
--- a/Source/gs/GSH_OpenGL/GSH_OpenGL.h
+++ b/Source/gs/GSH_OpenGL/GSH_OpenGL.h
@@ -54,6 +54,8 @@ class CGSH_OpenGL : public CGSHandler, public CGsDebuggerInterface
 
 	const VERTEX* GetInputVertices() const override;
 
+	void SetSpriteRoundingHackEnabled(bool enabled) override;
+
 protected:
 	void PalCache_Flush();
 	void LoadPreferences();
@@ -400,6 +402,7 @@ class CGSH_OpenGL : public CGSHandler, public CGsDebuggerInterface
 	bool m_forceBilinearTextures = false;
 	unsigned int m_fbScale = 1;
 	bool m_multisampleEnabled = false;
+	bool m_spriteRoundingHackEnabled = false;
 	bool m_depthTestingEnabled = true;
 	bool m_alphaBlendingEnabled = true;
 	bool m_alphaTestingEnabled = true;
diff --git a/Source/gs/GSH_OpenGLWin32/GSH_OpenGLWin32.cpp b/Source/gs/GSH_OpenGLWin32/GSH_OpenGLWin32.cpp
index dc34bcbb55..4d5c9926c1 100644
--- a/Source/gs/GSH_OpenGLWin32/GSH_OpenGLWin32.cpp
+++ b/Source/gs/GSH_OpenGLWin32/GSH_OpenGLWin32.cpp
@@ -69,7 +69,7 @@ void CGSH_OpenGLWin32::InitializeImpl()
 
 	if(wglSwapIntervalEXT)
 	{
-		wglSwapIntervalEXT(-1);
+		wglSwapIntervalEXT(1);
 	}
 
 	CGSH_OpenGL::InitializeImpl();
diff --git a/Source/gs/GSHandler.h b/Source/gs/GSHandler.h
index 66bfe59a65..e698d190ac 100644
--- a/Source/gs/GSHandler.h
+++ b/Source/gs/GSHandler.h
@@ -824,6 +824,13 @@ class CGSHandler
 	static void RegisterPreferences();
 	void NotifyPreferencesChanged();
 
+	// Default no-op. Only overridden by renderer backends (e.g. CGSH_OpenGL)
+	// that implement the sprite boundary rounding hack for specific arcade
+	// titles (tekken4/tekken5/taiko series) to fix vertical line seams.
+	virtual void SetSpriteRoundingHackEnabled(bool enabled)
+	{
+	}
+
 	void SetIntc(CINTC*);
 	void Reset();
 	virtual void SetPresentationParams(const PRESENTATION_PARAMS&);
diff --git a/Source/ui_shared/ArcadeUtils.cpp b/Source/ui_shared/ArcadeUtils.cpp
index 9ab3f8b6ea..3c03bb75b3 100644
--- a/Source/ui_shared/ArcadeUtils.cpp
+++ b/Source/ui_shared/ArcadeUtils.cpp
@@ -282,10 +282,8 @@ void ArcadeUtils::RegisterArcadeMachines()
 		return;
 	}
 
-	//This set is used to track inactive arcadedefs we might have in the database
 	std::set<fs::path> inactiveArcadeDefs;
 
-	//Collect all arcadedef files we have registered in the database
 	{
 		auto arcadeBootables = BootablesDb::CClient::GetInstance().GetBootables(BootablesDb::CClient::SORT_METHOD_ARCADE);
 		for(const auto& bootable : arcadeBootables)
@@ -298,7 +296,6 @@ void ArcadeUtils::RegisterArcadeMachines()
 	{
 		auto arcadeDefPath = entry.path();
 		auto arcadeDefFilename = arcadeDefPath.filename();
-		//Remove this arcadedef from the inactive set
 		inactiveArcadeDefs.erase(arcadeDefFilename);
 		try
 		{
@@ -313,7 +310,6 @@ void ArcadeUtils::RegisterArcadeMachines()
 		}
 	}
 
-	//Prune any remaining arcadedef
 	for(const auto& inactiveArcadeDef : inactiveArcadeDefs)
 	{
 		BootablesDb::CClient::GetInstance().UnregisterBootable(inactiveArcadeDef);
@@ -322,14 +318,12 @@ void ArcadeUtils::RegisterArcadeMachines()
 
 static CNamcoSys246Driver g_sys246Driver;
 static CNamcoSys147Driver g_sys147Driver;
-// clang-format off
 static CArcadeDriver* g_drivers[] =
-{
-	nullptr,
-	&g_sys246Driver,
-	&g_sys147Driver,
+    {
+        nullptr,
+        &g_sys246Driver,
+        &g_sys147Driver,
 };
-// clang-format on
 
 void ArcadeUtils::BootArcadeMachine(CPS2VM* virtualMachine, const fs::path& arcadeDefFilename)
 {
@@ -355,6 +349,19 @@ void ArcadeUtils::BootArcadeMachine(CPS2VM* virtualMachine, const fs::path& arca
 	driver->PrepareEnvironment(virtualMachine, def);
 	driver->Launch(virtualMachine, def);
 
+	{
+		bool spriteRoundingHackEnabled =
+		    (def.id.rfind("tekken4", 0) == 0) ||
+		    (def.id.rfind("tekken5", 0) == 0) ||
+		    (def.id.rfind("soulclb3", 0) == 0) ||
+		    (def.id.rfind("taiko", 0) == 0);
+
+		if(auto gsHandler = virtualMachine->GetGSHandler())
+		{
+			gsHandler->SetSpriteRoundingHackEnabled(spriteRoundingHackEnabled);
+		}
+	}
+
 	ApplyPatchesFromArcadeDefinition(virtualMachine, def);
 	ApplyIdleLoopBlocksFromArcadeDefinition(virtualMachine, def);