- •Apple Silicon combines CPU, GPU, Neural Engine, and RAM onto a single System-on-Chip (SoC) using Unified Memory Architecture (UMA).
- •Activity Monitor displays two distinct CPU core clusters: Performance Cores (P-cores) for foreground heavy tasks and Efficiency Cores (E-cores) for background services.
- •MacBook Air (M1, M2, M3) has no internal fan. When it heats up, it thermal throttles silently without any fan noise — Activity Monitor shows this via reduced clock efficiency.
- •Traditional 'Free RAM' metrics do not apply to Unified Memory; macOS compresses RAM dynamically and shares it between CPU and GPU.
- •Vitals Buddy breaks down Apple Silicon metrics into native core usage, SoC package power in Watts, and memory pressure.
The Apple Silicon Shift: How SoC Changes System Monitoring
When Apple transitioned the Mac lineup from Intel x86 processors to custom Apple Silicon (beginning with the revolutionary M1 chip and continuing through M2, M3, M4, and M5), the underlying hardware architecture fundamentally changed.
On older Intel Macs, the CPU, separate dedicated GPU (AMD/Nvidia), and system RAM were separate chips on the motherboard communicating over PCIe buses. On Apple Silicon, everything resides on a single unified piece of silicon: the System on Chip (SoC).
Because of this, reading Activity Monitor requires a different understanding of processor scheduling and memory allocation.
P-Cores vs E-Cores: How macOS Schedules Tasks
Every Apple Silicon chip features two types of processor cores:
In Activity Monitor (Window > CPU History), you can see separate vertical bars for each core. Notice how background processes rarely touch the P-cores — the macOS scheduler deliberately pins them to E-cores to preserve battery life on your MacBook Air or Pro.
- →Performance Cores (P-Cores): Ultra-wide, high-frequency execution engines designed for heavy, single-threaded or bursty tasks like compiling code, rendering 4K video, or running games.
- →Efficiency Cores (E-Cores): Compact, low-power cores that consume a fraction of the electricity, designed to handle audio playback, Time Machine backups, cloud syncing, and background daemon execution.
Unified Memory (UMA): Why 'Free RAM' is a Myth on Apple Silicon
On Apple Silicon, memory is not split into 'System RAM' and 'VRAM' (video memory). Both the CPU and GPU access the same Unified Memory pool with ultra-high bandwidth (up to 400–800 GB/s on Pro and Max chips).
This has two huge implications in Activity Monitor:
- →GPU allocations show up in system memory: When you run a graphics-heavy application or local LLM (like Ollama or MLX), the weights live directly in system RAM.
- →Zero Copy overhead: The CPU and GPU can read the same buffer without duplicating it across a PCIe bus.
- →Aggressive Caching: macOS keeps frequently used libraries in RAM indefinitely. Having 500MB 'Free' on a 16GB Mac is perfectly normal and desirable.
MacBook Air Silent Throttling vs MacBook Pro Active Cooling
One of the biggest differences between the MacBook Air (M1, M2, M3) and the MacBook Pro (M1–M5 Pro/Max) is active cooling.
The MacBook Air has NO internal cooling fan. It relies entirely on passive aluminum chassis heat dissipation. When running heavy sustained tasks (like exporting a 30-minute podcast or training a model), the Air reaches its thermal ceiling and silently reduces core clock speeds by 15%–30%.
Because there is no fan noise to warn you, you won't hear anything — your render will simply take longer. On a MacBook Pro, fans spin up to maintain full sustained clock speeds without thermal throttling.
Monitoring GPU & Apple Neural Engine (ANE)
Activity Monitor includes a '% GPU' column in the CPU tab, allowing you to see which application is utilizing the GPU cores.
For AI workloads (Whisper transcription, Stable Diffusion, Apple Intelligence models), macOS utilizes the on-chip Apple Neural Engine (ANE). While native Activity Monitor does not have a dedicated ANE tab, you can inspect it in Terminal with:
sudo powermetrics --samplers ane_power,gpu_power -n 1The Best System Monitoring Setup for Apple Silicon Users
Vitals Buddy was designed from day one specifically for Apple Silicon Macs. It natively interfaces with macOS Mach kernel APIs to read P/E-core utilization, SoC power, memory pressure, and thermal sensors before thermal throttling occurs.
All of this is presented in a sleek, native macOS design that feels right at home alongside Sequoia and Tahoe, without draining a single percent of your MacBook battery.
- →Individual P-Core and E-Core cluster utilization.
- →Real-time SoC package power consumption in Watts.
- →Unified Memory Pressure and Swap activity.
- →Internal thermal zone sensors before thermal throttling occurs.