diff --git a/src/spice2x/games/iidx/bi2a.cpp b/src/spice2x/games/iidx/bi2a.cpp
index 45b9d37..fff4962 100644
--- a/src/spice2x/games/iidx/bi2a.cpp
+++ b/src/spice2x/games/iidx/bi2a.cpp
@@ -195,11 +195,11 @@ bool games::iidx::IIDXFMSerialHandle::open(LPCWSTR lpFileName) {
         return false;
     }
 
-    log_info("iidx", "Opened COM2 (FM DEVICE)");
+    log_info("iidx", "Opened COM2 (FM DEVICE / bi2a)");
+    games::iidx::update_io_emulation_state(games::iidx::iidx_aio_emulation_state::bi2a_com2);
 
     // ACIO device
     acio_emu.add_device(new FMSerialDevice());
-
     return true;
 }
 
@@ -240,7 +240,7 @@ int games::iidx::IIDXFMSerialHandle::device_io(DWORD dwIoControlCode, LPVOID lpI
 }
 
 bool games::iidx::IIDXFMSerialHandle::close() {
-    log_info("iidx", "Closed COM2 (FM DEVICE)");
+    log_info("iidx", "Closed COM2 (FM DEVICE / bi2a)");
 
     return true;
 }
diff --git a/src/spice2x/games/iidx/bi2x_hook.cpp b/src/spice2x/games/iidx/bi2x_hook.cpp
index 3fdae2e..3755a1b 100644
--- a/src/spice2x/games/iidx/bi2x_hook.cpp
+++ b/src/spice2x/games/iidx/bi2x_hook.cpp
@@ -120,6 +120,11 @@ namespace games::iidx {
 
     static AIO_IOB2_BI2X_TDJ* __fastcall aioIob2Bi2xTDJ_Create(AIO_NMGR_IOB2 *nmgr, int a2) {
         if (!BI2X_PASSTHROUGH) {
+
+            log_info("bi2x_hook", "aioIob2Bi2xTDJ_Create called (TDJ I/O emulation active)");
+            games::iidx::update_io_emulation_state(
+                games::iidx::iidx_aio_emulation_state::bi2x_hook);
+
             custom_node = new AIO_IOB2_BI2X_TDJ;
             memset(&custom_node->data, 0, sizeof(custom_node->data));
 
diff --git a/src/spice2x/games/iidx/iidx.cpp b/src/spice2x/games/iidx/iidx.cpp
index 8d49b0f..51d5db4 100644
--- a/src/spice2x/games/iidx/iidx.cpp
+++ b/src/spice2x/games/iidx/iidx.cpp
@@ -80,6 +80,9 @@ namespace games::iidx {
     bool IIDXIO_LED_TICKER_READONLY = false;
     std::mutex IIDX_LED_TICKER_LOCK;
 
+    // io
+    static bool HAS_LIBAIO; // this is how we detect iidx27+
+
     tapeledutils::tape_led TAPELED_MAPPING[IIDX_TAPELED_TOTAL] = {
         { 19, Lights::StageLeftAvgR, Lights::StageLeftAvgG, Lights::StageLeftAvgB, "Stage Left" },
         { 19, Lights::StageRightAvgR, Lights::StageRightAvgG, Lights::StageRightAvgB, "Stage Right" },
@@ -311,13 +314,14 @@ namespace games::iidx {
             memcpy(settings2.interface_detail, interface_detail2, sizeof(interface_detail2));
             setupapihook_add(settings2);
 
-            // IIDX 25-27 BIO2 BI2A input device
+            // IIDX 25+ BIO2 BI2A input device
             devicehook_add(new IIDXFMSerialHandle());
         }
 
         // check for new I/O DLL
         auto aio = libutils::try_library("libaio.dll");
         if (aio != nullptr) {
+            HAS_LIBAIO = true;
 
             // check TDJ mode
             TDJ_MODE |= fileutils::text_read("C:\\000rom.txt") == "TDJ-JA";
@@ -895,4 +899,52 @@ namespace games::iidx {
 #endif
 
     }
+
+    void update_io_emulation_state(iidx_aio_emulation_state state) {
+        // <iidx27, don't care, since tdj wasn't a thing before
+        // this is also how we detect that iidx module is attached
+        if (!HAS_LIBAIO) {
+            return;
+        }
+
+        // in iidx27-30, most DLL types can handle both, caching things in nvram and possibly end
+        // up with wrong i/o (temporarily until nvram is initialized again)
+        // to avoid false positives, only do this for iidx31+, since we know for sure that iidx31
+        // has a clean 010/012 split
+        if (avs::game::is_ext(0, 2023101000)) {
+            return;
+        }
+
+        // log_warning below could be turned into log_fatal in the future once we gain confidence
+        // that this isn't triggering when it's not supposed to
+        if (state == iidx_aio_emulation_state::bi2a_com2 && TDJ_MODE) {
+            deferredlogs::defer_error_messages({
+                "IIDX I/O mode conflict",
+                "    game is currently configured to use LDJ I/O;",
+                "    however, you turned on IIDX TDJ Mode (-iidxtdj)",
+                "    two options to fix this:",
+                "      For TDJ mode (120Hz): import patches and enable Force TDJ Mode patch",
+                "      For LDJ mode (60Hz): turn off IIDX TDJ Mode option",
+                });
+            log_warning(
+                "iidx",
+                "game is using LDJ I/O but spice TDJ mode is turned on! "
+                "enable Force TDJ I/O patch, OR turn off -iidxtdj");
+        } else if (state == iidx_aio_emulation_state::bi2x_hook && !TDJ_MODE) {
+            deferredlogs::defer_error_messages({
+                "IIDX I/O mode conflict",
+                "    game is currently configured to use TDJ I/O;",
+                "    however, you turned off IIDX TDJ Mode (-iidxtdj)",
+                "    two options to fix this:",
+                "      For TDJ mode (120Hz): turn on IIDX TDJ Mode option",
+                "      For LDJ mode (60Hz): import patches and enable Force LDJ Mode patch",
+                });
+            log_warning(
+                "iidx",
+                "game is using TDJ I/O but spice TDJ mode is turned off! "
+                "turn on -iidxtdj, OR enable Force LDJ I/O patch");
+        } else {
+            log_misc("iidx", "i/o mode validation passed");
+        }
+    }
 }
diff --git a/src/spice2x/games/iidx/iidx.h b/src/spice2x/games/iidx/iidx.h
index 623ecf4..0ec9662 100644
--- a/src/spice2x/games/iidx/iidx.h
+++ b/src/spice2x/games/iidx/iidx.h
@@ -62,4 +62,10 @@ namespace games::iidx {
     const char* get_16seg();
     bool is_tdj_fhd();
     void apply_audio_hacks();
+
+    enum class iidx_aio_emulation_state {
+        bi2a_com2,
+        bi2x_hook
+    };
+    void update_io_emulation_state(iidx_aio_emulation_state state);
 }
diff --git a/src/spice2x/launcher/options.cpp b/src/spice2x/launcher/options.cpp
index bbaa572..8a7f814 100644
--- a/src/spice2x/launcher/options.cpp
+++ b/src/spice2x/launcher/options.cpp
@@ -590,7 +590,7 @@ static const std::vector<OptionDefinition> OPTION_DEFINITIONS = {
         .category = "Game Options (Advanced)",
     },
     {
-        .title = "IIDX TDJ Mode",
+        .title = "IIDX TDJ Mode (Lightning Model)",
         .name =  "iidxtdj",
         .desc = "Enables TDJ cabinet mode. Ensure you also set -iidxsounddevice to desired option",
         .type = OptionType::Bool,