i5-12600 Core 3 Saturation & Sluggish Gameplay (Tested across Clean Win 11, 3x CPUs & 2x MotherBoards)

System Specifications: • CPU: Intel Core i5-12600 (Normal/healthy temperatures under load, no thermal throttling) • Motherboard: ASUS TUF Gaming B760M-Plus D4 WiFi (Replaced via RMA) • GPU: NVIDIA GeForce RTX 5060 Ti • Power Supply: Corsair RM850e • Additional NIC: Intel Ethernet Server Adapter I210-T1 PCIe • RAM: 32GB (2x16GB) DDR4 • Storage: Tested across 2 different NVMe SSDs • OS: Windows 10 Pro & Windows 11 Pro (Both clean installed from scratch, fully updated) • Display: MSI MAG 276CXF (27" Rapid VA 280Hz) • Peripheral Polling Rate: Mouse capped at 500Hz

I am experiencing severe micro-stutters, frame-time spikes (up to 18ms), abrupt 0.1% Low FPS drops (dropping from ~230 FPS down to 70 FPS), and a distinct feeling of gameplay sluggishness/heavy input lag when attempting to maintain the native smoothness of a 280Hz display.

This issue occurs exclusively in Slither.io (whether running via Chromium/NW.js Canvas or a native C++/Vulkan client). In significantly more demanding titles like Dead by Daylight, the system runs completely smooth with no stutters or drops.

Core Workload & Task Manager Graph Anomalies

1. Progressive Core 3 Saturation (P-Core Bottleneck): • In map areas with high activity (orbs and snakes), Core 3 utilization steadily climbs from 60% to 80%. • Suddenly, Core 3 hits 100% continuous saturation. At this point, frame drops worsen drastically and severe micro-stutters occur continuously.

Synchronized Needle/Wave Spikes: • Task Manager exhibits recurring wave/needle-shaped spikes. • These spikes occur simultaneously at the exact same millisecond across all CPU core graphs, the Network (Ethernet) graph, and the GPU 3D engine graph.

Thread Asymmetry (Hyper-Threading): • When HT is enabled, odd logical cores maintain near-idle utilization while even physical cores sustain heavy, unbalanced loads.

Cross-System Baseline Comparisons

• Wife's PC (i3-10100F): Processor core utilization remains completely uniform and steady under identical gameplay, with no single core ever exceeding normal thresholds. • Friends' PCs (i5-11400 & i9-9900K): Maintain completely flat, smooth CPU usage graphs with zero core lockups.

Operating System & Driver Testing (Windows 10 vs Windows 11)

To rule out Windows 10 scheduling limitations with Alder Lake architecture:

Performed clean installations of Windows 10 across multiple official ISO builds.

Upgraded to and subsequently performed a complete clean format/installation of Windows 11 from scratch on a wiped NVMe SSD.

Manually installed and updated all official drivers (Intel Chipset, Intel Management Engine, NVIDIA GPU drivers, Intel LAN drivers, and motherboard BIOS).

Result: The issue persists identically on Windows 11 with the latest drivers. Core 3 continues to hit 100% saturation, synchronized graph spikes still occur across CPU/GPU/Network, and gameplay remains sluggish.

Complete Hardware & Troubleshooting History

2x Intel CPU RMAs: Processors replaced twice through Intel official RMA process (tested across 3 different i5-12600 CPUs); identical behavior across all units.

1x Motherboard RMA: ASUS B760M motherboard replaced with a brand-new unit via RMA.

Power Supply: Replaced with a new Corsair RM850e PSU.

Storage: Clean OS installations tested across 2 independent NVMe SSDs.

Network Testing & Interrupt Isolation: • Onboard Realtek RTL8125 2.5GbE NIC showed high hardware interrupts during point-to-point NTTTCP stress testing. • Installed a dedicated Intel I210-T1 PCIe NIC to isolate interrupts. The simultaneous Task Manager spikes and frame drops persist identically even on the dedicated Intel server card.

Diagnostics & BIOS Tweaks: • LatencyMon confirms low/normal DPC latency during active gameplay (no failing third-party drivers). • Tested Hyper-Threading (Enabled/Disabled), C-States, C1E, Intel SpeedShift, and PCIe ASPM manually. • Tested with XMP enabled and disabled (JEDEC stock frequency). • Tested across current and older BIOS versions. • Applied registry optimizations (NetworkThrottlingIndex=ffffffff, SystemResponsiveness=0, MSI Mode enabled on GPU/NIC, VBS/Memory Integrity disabled).

Correlation with Known Intel Community Case

This behavior mirrors the thread allocation issue documented in the Intel Community thread: https://community.intel.com/t5/Mobile-and-Desktop-Processors/Windows-10-Why-does-12600k-park-so-many-cores-Cores-are-not/m-p/1339478