diff --git a/cpu/ppc/ppcemu.h b/cpu/ppc/ppcemu.h
index 7256f6c7a6..297b0f75f0 100644
--- a/cpu/ppc/ppcemu.h
+++ b/cpu/ppc/ppcemu.h
@@ -375,6 +375,15 @@ extern bool include_601;   // For non-PowerPC 601 emulation with 601 extras
 extern bool is_altivec;    // For Altivec Emulation
 extern bool is_64bit;      // For PowerPC G5 Emulation
 
+enum class PPCPowMode : uint8_t {
+    None,
+    Unconditional,
+    HID0,
+};
+
+extern PPCPowMode ppc_pow_mode;
+extern uint32_t ppc_pow_hid0_mask;
+
 // Make execution deterministic (ignore external input, used a fixed date, etc.)
 extern bool is_deterministic;
 
diff --git a/cpu/ppc/ppcexec.cpp b/cpu/ppc/ppcexec.cpp
index 45fa5c656a..92b6e5de9e 100644
--- a/cpu/ppc/ppcexec.cpp
+++ b/cpu/ppc/ppcexec.cpp
@@ -58,6 +58,15 @@ MemCtrlBase* mem_ctrl_instance = 0;
 
 bool is_601 = false;
 bool include_601 = false;
+PPCPowMode ppc_pow_mode = PPCPowMode::None;
+uint32_t ppc_pow_hid0_mask = 0;
+
+// 603/7xx HID0 power-saving mode bits. They are selected in HID0,
+// then entered by setting MSR[POW] with mtmsr.
+static constexpr uint32_t HID0_DOZE  = 0x00800000;
+static constexpr uint32_t HID0_NAP   = 0x00400000;
+static constexpr uint32_t HID0_SLEEP = 0x00200000;
+static constexpr uint32_t HID0_POWER_SAVE_MASK = HID0_DOZE | HID0_NAP | HID0_SLEEP;
 
 bool is_deterministic = false;
 
@@ -917,6 +926,27 @@ void ppc_cpu_init(MemCtrlBase* mem_ctrl, uint32_t cpu_version, bool do_include_6
     ppc_state.spr[SPR::PVR] = cpu_version;
     is_601 = (cpu_version >> 16) == 1;
     include_601 = !is_601 & do_include_601;
+    ppc_pow_mode = PPCPowMode::None;
+    ppc_pow_hid0_mask = 0;
+
+    switch (cpu_version) {
+    case PPC_VER::MPC603:
+    case PPC_VER::MPC603E:
+    case PPC_VER::MPC603EV:
+    case PPC_VER::MPC750:
+        // 603/7xx enter power-saving modes through HID0 doze/nap/sleep
+        // bits selected before MSR[POW] is set.
+        ppc_pow_mode = PPCPowMode::HID0;
+        ppc_pow_hid0_mask = HID0_POWER_SAVE_MASK;
+        break;
+    case PPC_VER::MPC604:
+    case PPC_VER::MPC604E:
+        // 604-family processors use MSR[POW] directly.
+        ppc_pow_mode = PPCPowMode::Unconditional;
+        break;
+    default:
+        break;
+    }
 
     initialize_ppc_opcode_table();
 
diff --git a/cpu/ppc/ppcopcodes.cpp b/cpu/ppc/ppcopcodes.cpp
index 8480c7b134..cec08290e2 100644
--- a/cpu/ppc/ppcopcodes.cpp
+++ b/cpu/ppc/ppcopcodes.cpp
@@ -30,13 +30,6 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
 #include <cinttypes>
 #include <vector>
 
-// MPC750 HID0 power-saving mode bits. They are selected in HID0, then
-// entered by setting MSR[POW] with mtmsr.
-static constexpr uint32_t HID0_DOZE  = 0x00800000;
-static constexpr uint32_t HID0_NAP   = 0x00400000;
-static constexpr uint32_t HID0_SLEEP = 0x00200000;
-static constexpr uint32_t HID0_POWER_SAVE_MASK = HID0_DOZE | HID0_NAP | HID0_SLEEP;
-
 //Extract the registers desired and the values of the registers.
 
 // Affects CR Field 0 - For integer operations
@@ -820,10 +813,26 @@ void dppc_interpreter::ppc_mtmsr(uint32_t opcode) {
         dec_exception_pending = false;
         //LOG_F(WARNING, "MTMSR: decrementer exception triggered");
         ppc_exception_handler(Except_Type::EXC_DECR, 0);
-    } else if ((ppc_state.msr & MSR::POW) &&
-               (ppc_state.spr[SPR::HID0] & HID0_POWER_SAVE_MASK)) {
-        exec_flags |= EXEF_SLEEP;
-        ppc_next_instruction_address = (ppc_state.pc & 0xFFFFFFFCUL) + 4;
+    } else if (ppc_state.msr & MSR::POW) [[unlikely]] {
+        bool enter_sleep = false;
+
+        switch (ppc_pow_mode) {
+        case PPCPowMode::Unconditional:
+            enter_sleep = true;
+            break;
+        case PPCPowMode::HID0:
+            enter_sleep = (ppc_state.spr[SPR::HID0] & ppc_pow_hid0_mask) != 0;
+            break;
+        case PPCPowMode::None:
+            break;
+        }
+
+        if (enter_sleep) {
+            exec_flags |= EXEF_SLEEP;
+            ppc_next_instruction_address = (ppc_state.pc & 0xFFFFFFFCUL) + 4;
+        } else {
+            mmu_change_mode();
+        }
     } else {
         mmu_change_mode();
     }