Computer Hardware Explained: CPU, RAM, Storage and Ports (Tech+)
What you’ll know
What each main part of a computer does, how to tell a fast drive from a slow one, which port is which, and how to see exactly what’s inside your own PC without opening it.
Why it matters. “My computer is slow” is the most common help desk ticket in the world. Knowing what the CPU, RAM and drive each do tells you where to look, and which upgrade would actually help.
Input, processing, output, storage
Every computer does four jobs: it takes input (keyboard, mouse, microphone), processes it (the CPU), shows output (screen, speakers, printer) and stores the results (drive). Each part below fits one of those jobs.
The main parts
| Part | What it does | What to look at |
|---|---|---|
| CPU (processor) | Runs every instruction. The “brain”. | Cores (workers), threads (tasks it can juggle; often 2 per core), clock speed in GHz. |
| RAM (memory) | Holds whatever is open right now. Wiped when the power goes off (it’s volatile). | Size in GB. Too little RAM is the classic cause of a slow PC with lots of tabs open. |
| Storage (drive) | Keeps files when the power is off (non-volatile). | Type (HDD, SATA SSD, NVMe SSD) and capacity. |
| Motherboard | Connects every part together. | Which sockets, slots and ports it supports. |
| GPU (graphics) | Draws the screen; also runs games and AI work. | Built into the CPU (integrated) or a separate card (dedicated). |
| PSU (power supply) | Turns wall power into the voltages the parts need. | Wattage; a failing PSU causes random shutdowns. |
Hard drive vs SSD vs NVMe
| Type | How it works | Typical speed | Good to know |
|---|---|---|---|
| HDD | Spinning magnetic platters and a moving arm | ~100 to 250 MB/s | Cheap per TB, but slow to start programs and fragile if dropped. |
| SATA SSD | Flash memory on the older SATA connection | up to ~550 MB/s | No moving parts. Huge upgrade over an HDD. |
| NVMe SSD | Flash memory on the fast PCIe bus (usually an M.2 stick) | ~3,000 to 7,000+ MB/s | The fastest common option in new PCs. |
Ports you’ll meet
| Port | Used for |
|---|---|
| USB-A | The classic rectangular USB plug: keyboards, mice, flash drives. |
| USB-C | Small reversible plug. Depending on the device it can carry data, video and charging power. |
| Thunderbolt | Uses the same USB-C shape but is faster and can run docks and multiple displays. Look for the lightning-bolt icon. |
| HDMI | Video and audio to TVs and monitors. |
| DisplayPort | Video to monitors; common on PCs and graphics cards. |
| RJ45 (Ethernet) | Wired network. See cabling and connectors explained. |
| 3.5 mm audio | Headphones and microphones. |
Nova counted the cores in my laptop and said “eight workers, sixteen threads.” I said that sounds like a union. She did not laugh. The CPU did, sixteen times. — Nyx
Try it: see what’s inside your PC
PS> Get-CimInstance Win32_Processor | Select-Object Name,NumberOfCores,NumberOfLogicalProcessors PS> [math]::Round((Get-CimInstance Win32_ComputerSystem).TotalPhysicalMemory/1GB,1) PS> Get-PhysicalDisk | Select-Object FriendlyName,MediaType,BusType
The first line shows your CPU, its cores and its logical processors (threads). The second shows RAM in GB. The third lists each drive: MediaType says SSD or HDD, and BusType NVMe means the fast kind. Prefer clicking? Open Task Manager (Ctrl + Shift + Esc) and choose Performance.
$ lscpu | grep -E 'Model name|^CPU\(s\)' $ free -h $ lsblk -d -o NAME,ROTA,TRAN,SIZE
In lsblk, ROTA 1 means a spinning (rotational) drive and 0 an SSD, and TRAN nvme marks an NVMe drive. Inside WSL or a virtual machine you’ll see virtual disks instead of your real ones, and they can report ROTA 1 even on an SSD. On a Mac, use Apple menu > About This Mac.
Where this fits
This is part of the free CompTIA Tech+ roadmap: computer basics in the order the exam teaches them.
NextOperating systems, software and file systems→
Go deeper
- Binary, hex and data sizes — why drive sizes look smaller
- Cabling and connectors — RJ45, fiber and the rest
- Wi-Fi troubleshooting on Windows — the other half of “my computer is slow”
Explainer, written by StashGrid with AI help and checked against the CompTIA Tech+ (FC0-U71) exam objectives before publishing. Every command was run on a Windows 11 PC and in Ubuntu 24.04 (WSL) on 30 Oct 2026. StashGrid isn’t affiliated with CompTIA. Spotted an error? Tell us.