When a PC gets slow, loud, or hot, most people start guessing — reinstalling Windows, buying RAM, or replacing parts that were never the problem. After years of fixing machines, I work through the same checklist in the same order, because the boring causes explain about 90% of cases.
1. Heat first, always
An overheating PC throttles itself, and throttling looks exactly like "my computer is just old now." Before anything else, check your temperatures under load and compare them with your idle baseline. I wrote up the full method here: how to check your CPU and GPU temperatures. If it's hot, the usual chain is dust, blocked vents, dried thermal paste, and fans following a silence-first factory curve. On fan curves specifically, this piece on how fan control software keeps a PC cool and quiet is worth five minutes.
Dust deserves its own step because people skip it for years: how to clean dust from a laptop covers the safe way to do it and how often it actually matters.
2. Boot and startup
A machine that takes minutes to boot is usually drowning in startup apps, not dying. Work through the startup list, drive health, and Fast Startup quirks in order — the full sequence is in this Windows 11 slow boot guide.
3. Storage health and space
A failing drive gets slower long before it dies. Check the health status before you blame Windows, and if you're still on a spinning disk, the SSD vs HDD comparison explains why an SSD is still the single biggest upgrade for an old machine.
4. Crashes and freezes
Random restarts and blue screens have specific causes — overheating, bad RAM, driver faults, power issues — and each leaves evidence. For restarts, start with why your computer randomly restarts; for blue screens, this BSOD cause-finding guide shows how to read the error instead of guessing.
5. The "suddenly slow" laptop
When a laptop slows down overnight, the shortlist is short: a stuck update, a runaway process, malware, or heat. This walkthrough of why a laptop is suddenly slow goes through the checks in order.
Keep the right tools around
Half of diagnosis is having the right free utilities installed before something breaks. This list of 5 free tools every Windows user should know is the kit I install on every machine I touch. The rest of my guides live at The PC Fix Guide.
Work the checklist in order and you'll find the real cause most of the time — no parts cannon required.
