ASUS ROG Strix G16 G615LP (Ultra 9 275HX + RTX 5070) — Performance Issue Occurring Only in Games, Persisting Until a Restart

I’m experiencing a strange issue with the laptop I’ve been using for a year, and I wanted to ask if anyone else has encountered it. This problem has reached the point of driving me crazy. How can I resolve this?

The Issue: In CPU-intensive games like CS2 and Project Zomboid (mostly CS2, but occasionally others), after playing for a while, I experience severe stuttering and input lag, even though the FPS appears high. Strangely, the issue never triggers when I run a heavy stress test on the same processor; it only happens during gaming. Once triggered, even if I exit the game, the CPU temperature gets stuck at 60–70°C on the desktop (whereas it’s normally 50–60°C), and the fans speed up accordingly. It doesn't resolve no matter how long I wait—only a simple restart fixes it. Tests performed so far: After triggering the issue, I ran Cinebench 2026 and logged data with HWiNFO without restarting; then, I restarted and repeated the same test. The score difference was 5300 vs. 7350 (a 28% difference). (The normal single-core score is 527; after the issue occurs, it drops to 160.) Interestingly, while in the "bugged" state, temperature and power consumption were actually lower, yet clock speeds were higher—meaning this isn't classic "thermal throttling"; the CPU runs at the same speed but performs significantly less work. I also captured separate HWiNFO logs while idling on the desktop (in both bugged and normal states). The difference is stark: CPU power consumption is 12.2W in the bugged state versus 5.8W in the normal state. The rate at which P-cores enter the deep sleep state (C7) is 83.7% normally, but only 2.2% when bugged. In other words, the cores fail to fully shut down even at idle, generating excess heat and power consumption.

I tested it using the Intel Processor Diagnostic Tool in both the buggy and non-buggy states, and it passed in both instances. Locking PL2 to 55W initially solved the problem completely, but it stopped working over time; the issue now triggers even when the limit is applied. Possible causes I'm considering: It isn't classic thermal throttling (PROCHOT) or a PL1/PL2 power limit issue; neither of these shows up as triggered in the logs. The data points to a "stuck" state within the CPU's EC/VRM subsystem (voltage/current management) that doesn't reset without a system restart. I’ve also ruled out Windows-side issues (powercfg shows no active "stay awake" requests), so it doesn't appear to be a simple software or service problem. None of the BIOS or driver updates provided a permanent fix.