Phase 2 · Free

2.1 The Parts Inside a Computer

Every desktop, laptop, server, and phone is built from the same handful of parts. A good way to hold them in your head is a kitchen: the CPU is the cook, RAM is the counter, and storage is the pantry.

25 minPhase 2: Know Your HardwareFree

Phase 2: Know Your Hardware. Lesson 1 of 4. About 25 minutes.

Plain entry

Every desktop, laptop, server, and phone is built from the same handful of parts. A good way to hold them in your head is a kitchen:

  • The CPUCentral Processing Unit: the chip that executes program instructions, measured by its cores, threads, clock speed, and cache. Read more → is the cook.
  • RAMRandom Access Memory: the fast, temporary working memory that holds the programs and data a computer is using right now, cleared when power is lost. Read more → is the counter: fast, close, and wiped clean when the power goes out.
  • Storage is the pantry: slower, much bigger, and it keeps everything overnight.
  • The motherboardThe main circuit board that connects every part of a computer, including the CPU, memory, storage, and expansion cards, and holds the system firmware. Read more → is the kitchen itself, the floor and wiring everything sits on.
  • The power supply is the gas line.

That is as far as the kitchen goes. The rest of this lesson is the real thing.

Terms

  • CPU (Central Processing Unit): runs instructions. Has cores (independent workers) and threads (a core can juggle two with hyper-threading or SMT).
  • Clock speed: how many cycles per second a core runs, in GHz. Not comparable across CPU generations on its own.
  • Cache: small, very fast memory on the CPU itself (L1, L2, L3).
  • RAM (Random Access Memory): working memory. Volatile: erased at power off. Measured in GB; type is DDR4 or DDR5 on current machines.
  • Storage: persistent data. HDD (spinning disk), SATASerial ATA: the long-standing interface for connecting hard drives, SSDs, and optical drives, with a practical speed limit of about 550 MB/s. Read more → SSDSolid-State Drive: storage that keeps data on flash memory chips with no moving parts, making it far faster and more durable than a spinning hard drive. Read more → (flash on the old disk connector), NVMeNon-Volatile Memory Express: a storage protocol built for flash SSDs that talks to the CPU over PCIe, delivering far more speed and lower latency than SATA. Read more → SSD (flash straight on the fast PCIePCI Express: the high-speed connection inside a computer that links the CPU to graphics cards, NVMe drives, network cards, and other expansion devices. Read more → bus).
  • Motherboard: the main circuit board. Holds the CPU socket, RAM slots, firmwareLow-level software stored on a chip inside a device that controls the hardware directly and runs before any operating system loads. Read more → chip, and connectors.
  • PSUPower Supply Unit: the component that converts wall power (AC) into the steady low-voltage DC power that a computer's parts need. Read more → (Power Supply Unit): turns wall AC into the DC voltages the parts need. Rated in watts.
  • GPU (Graphics Processing Unit): draws the screen; also does parallel math for AI and video. Either built into the CPU (integrated) or a separate card (discrete).
  • NIC (Network Interface Card): the network connection, wired or Wi-Fi. Has a MAC address.

Depth: what each part decides about your machine

PartIf it is too small or slow, you seeWhere Linux reports it
CPUFans loud, everything slow under load, high load averagelscpu, top
RAMFine at first, then everything crawls as it swaps to diskfree -h
StorageSlow boot, slow app launch, “disk full” errorslsblk, df -h
GPUChoppy video, display problemslspci
NICSlow or dropping networkip link
PSURandom shutdowns under load, no power at allNot visible from Linux; it is a physical check

A rule worth keeping: most “slow computer” complaints are RAM or storage, not CPU. A five-year-old CPU with an SSD and enough RAM feels faster than a new CPU on a spinning disk with too little RAM.

The VM catch

In a virtual machine, the guest sees what the hypervisor gives it, not your real hardware. Your VM might report 2 CPUs and 4 GB RAM on a host with 8 cores and 32 GB. Disks show up as a generic VirtualBox or QEMU device. That is not a bug. It is the point of a VM, and it is a good thing to notice and write down in the lab.

Going further

The CPU does not talk to storage directly. Data goes storage to RAM to cache to the CPU’s registers. Each step is roughly 10 to 1000 times faster than the one before. Programs that are “slow” are usually waiting on one of those steps, not computing. The OS Fundamentals track covers memory hierarchy and caching in detail; the BytesNation Dictionary has a primer on caching and latency.

Why it works this way

Every part is a trade between speed, size, and cost. CPU cache is tiny and very fast, RAM is bigger and slower, disk is huge and slower still. The machine moves data down that ladder as it needs it. Most “my computer is slow” problems are one rung of that ladder running out, which is why the next lessons teach you to measure each part instead of guessing.

Self-check

  1. Which part loses its contents at power off?
  2. A user’s laptop is slow only when many browser tabs are open. Most likely part?
  3. What is the difference between a SATA SSD and an NVMe SSD?
  4. Why does your VM report fewer CPUs than your real computer has?

Answers: (1) RAM. (2) RAM. (3) Same flash memory, but NVMe sits on the much faster PCIe bus. (4) The hypervisor only gives the guest what you assigned.

Sources