u/Mammoth_Relative_677

Built a new AM5 system recently and started getting a very strange issue where the CPU would randomly drop to ~0.5 GHz for around 30 seconds to 1 minute, making the entire PC extremely laggy. The weird part is that it ONLY happens during very light usage like Chrome/YouTube, never during gaming or benchmarks.

Current specs:

• Ryzen 5 7600
• ASUS TUF GAMING B650M-PLUS WIFI
• RTX 5080
• 64GB DDR5 XPG Lancer Blade 5600 CL46
• Be Quiet Pure Power 12 M 1000W
• Thermalright Phantom Spirit SE
• Windows 11

What happened:

• Initially had some EXPO instability and weird POST behavior
• At one point Windows recovery complained about corruption
• CPU clocks were observed dropping as low as ~66 MHz in HWiNFO logs
• Chrome usage could trigger severe lag/stutter
• Gaming and Cinebench were always stable

What I already tried:

• BIOS Optimized Defaults
• SFC / DISM / CHKDSK
• Reinstalled AMD chipset drivers
• Enabled EXPO again successfully
• Enabled PBO
• Multiple Cinebench runs and long gaming sessions
• Monitoring with HWiNFO logs for hours

Findings:

• No thermal throttling
• Temps always normal (~70–75C under load)
• No PROCHOT
• No PPT/EDC limit issues
• Cinebench multicore stays around 4.9–5 GHz stable
• Diablo 4 Ultra RT at 1440p runs fine (~145 FPS with FG, 100 1% lows)

The ONLY remaining issue is:
Random extreme downclocking during idle/light load scenarios (mostly Chrome/YouTube/background usage).

At this point it seems related to:

• Ryzen idle states / C-states
• Power management
• BIOS/AGESA behavior
• Scheduler interactions

Has anyone else experienced this specifically on AM5 where the system is perfectly stable under load but randomly collapses in idle/light desktop usage?