Xemu Complex 4627 Hot

Late last night, the Xemu core team pushed a hotfix (Build 4628) with a single line in the changelog:

"Re-enabled thermal throttling guard for Complex 4627. If you see 'HOT' in the overlay, your system is saving itself. Do not disable this flag."

They also introduced a new visual overlay: When the emulation enters a "hot path," the screen border turns amber, and the FPS counter swaps to a thermal wattage meter.

A data center technician received a failed Northbridge chip on a Complex 4627 board. Standard reflow (peak 250°C) failed three times—solder would wet on one side but not the other. xemu complex 4627 hot

Upon switching to the Xemu Complex 4627 hot profile (270°C peak, 60s TAL), the technician observed:

The key variable was the bottom IR setpoint (210°C), which compensated for the 2.2mm board thickness.

The Xemu Discord server and Reddit’s r/emulation have extensive threads on "Complex 4627 hot". Here are the top user-reported solutions: Late last night, the Xemu core team pushed

"I fixed mine by replacing my Xbox BIOS with the 'no_thermal_4627' version. Turns out my BIOS dump was corrupted." – u/OGXboxArchivist

"For me, it was the audio driver. I switched from ASIO to DirectSound in Windows and the error vanished." – @xemu_user_42

"Complex 4627 is a meme at this point. Just add --ignore-trip and monitor your actual CPU temps. If they're fine, ignore the error." – Discord user: EmiNation "Re-enabled thermal throttling guard for Complex 4627

The original Xbox had a rudimentary thermal sensor near the MCPX chip. Xemu faithfully emulates this sensor. However, due to bugs in version 0.7.x and earlier, the emulated temperature would spike to 100°C for no reason, triggering a "4627 hot" fault even when your PC was cool.

Fix: Update Xemu to the latest nightly build. As of August 2024, the thermal model has been revised to prevent false positives.

The 4627 complex uses small 8mil vias under pads (VIPPO). A low-temperature profile requires longer reflow time, which actually increases thermal stress. The Xemu hot profile uses a shorter time above liquidus (60 sec vs 90 sec), reducing tenting blowouts.