Why Your PC Runs 20°C Hotter Than It Should

A PC running hot is almost never a dying machine. Nine times out of ten on the bench, the cause is the same boring pair: a cooler packed with dust, and thermal paste that dried out a year or two ago. The chips are fine. The cooling around them has quietly degraded to the point where it can no longer move the heat away fast enough, so the temperatures climb, the fans get loud, and the performance you paid for starts disappearing. On most machines this is a cleaning job, not a reason to start shopping.

This is the single most common thing we fix with PC cleaning and thermal-paste service in Copenhagen, and it is worth understanding before you spend money on anything. Everything below is what the heat is actually doing inside the case, why it gets worse on an almost predictable timeline, and how to tell the cheap fix from the genuinely dead one. If you would rather skip to the fix, every PC and laptop service is listed with fixed prices up front.

What "running hot" actually costs you

Heat is not just a number in a monitoring app. It is the throttle on the performance you already paid for.

Every modern CPU and GPU has a temperature ceiling the manufacturer designs it to respect. According to Intel's processor specs, most desktop CPUs are built to run safely up to around 100°C, and they begin thermal throttling — deliberately dropping clock speed to shed heat — in the mid-to-high 90s. NVIDIA and AMD graphics cards do the same thing in their own range, typically backing off in the mid-80s. Throttling is not a fault. It is the protection working: the chip choosing a slower job over a dead one.

The problem is that throttling is invisible until you go looking for it. You do not get an error. You get a game that runs at 90 FPS for ten minutes and then sits at 45. You get a render or an export that takes half again as long as it used to. You get a desktop that feels fine until the moment you actually ask the machine to work. The chip is quietly protecting itself, and you are paying for performance that heat is throwing away.

Why it gets worse at one to two years old, almost on schedule

PCs do not overheat suddenly. They spend roughly a year getting quietly hotter, and almost nobody notices until a hot day or a heavy game finally tips it over. Two things happen on a predictable timeline.

Dust builds up where it does the most damage. A desktop pulls cool air in, pushes it across a fine metal radiator called the heatsink fin stack, and exhausts the hot air out the back. Those fins sit a fraction of a millimetre apart. Over twelve to twenty-four months of normal use they pack with a felt-like mat of dust, hair and pet fur. Air can no longer pass through, so the fans spin faster and louder to compensate — which is why a "suddenly loud" PC is usually a clogged one. The noise is the first symptom, not a separate problem.

Thermal paste dries out. Between each chip and its cooler sits a thin layer of thermal paste that carries heat across the microscopic gap between them. From the factory it is soft and conductive. Over a year or two of heat cycling it dries, cracks, and pumps out from between the surfaces. Once that happens the cooler can be spotless and still fail, because the heat cannot cross the gap to reach it in the first place.

Put those together and you get a machine that was fine at launch running 15-25°C hotter doing the exact same thing, on the same settings, in the same room. Nothing "broke". The cooling just silently degraded past the point where it could keep up.

How to tell a cheap fix from a dead machine

Most of the time this is the cheapest repair there is. Occasionally it is not, and you deserve to know which before you pay anyone. Here is the honest split.

Symptom	What it usually means	Realistic fix
Fans loud, FPS or speed drops under load, then recovers at idle	Dust and old paste — classic heat soak	Clean and repaste
Hot and throttling only during games, rendering, heavy work	Airflow restricted past the throttle point	Clean and repaste
Hot and throttling even sitting idle on the desktop	Paste pumped out, or a failing fan	Clean, repaste, possibly a fan
Shuts off instantly with no load, random restarts	Likely not heat — could be power, RAM or board	Diagnosis first, not a clean
Burning-plastic smell, or visible scorch on the board	Stop using it now	Diagnosis first

The pattern that means "cheap fix" is simple: it behaves under load and recovers at idle. The pattern that means "get it looked at properly first" is when it misbehaves cold, doing nothing. Heat problems are load problems. If yours acts up at idle, the heat is probably a symptom of something else, and a cleaning alone will not solve it — which is exactly what an honest crash and blue-screen diagnosis is there to rule out before you spend on parts.

What to actually do — cheapest steps first

Work down this list. Stop when it is fixed.

1. Give the case room to breathe. A PC shoved into a closed desk cubby or against a wall is recycling its own hot exhaust. Pulling it into open air and clearing the vents can drop temperatures several degrees for free. Do this first, every time.
2. Check the fan curve. Many prebuilts and motherboards ship in a "quiet" or "silent" profile that caps fan speed to stay quiet — at the cost of heat. The BIOS or the maker's app usually has a "performance" or "standard" fan curve. Turning it up costs nothing.
3. Blow out the dust — gently. A short burst of compressed air through the cooler and the front intake clears some surface dust. Hold the fans still with a finger so they do not spin and generate voltage. This helps a little. It does not reach the packed fin stack or do anything for dried paste, which is where the real heat is trapped.
4. Get it cleaned and repasted. This is the real fix and the one that lasts. The cooler comes off, the fins and fans are cleaned out properly, fresh paste goes on the CPU (and the GPU if it needs it), and it goes back together. On a typical neglected desktop this brings load temperatures down 15-25°C and the throttling stops.

Step four is what GGFix's PC cleaning and thermal-paste service is: a fixed 599 DKK Express Clean with a CPU repaste, or a 999 DKK Deep Clean with full strip-down and a before/after temperature report so you can see the exact drop. It is the same work on a gaming rig, which is why an overheating gaming laptop follows the same diagnosis we cover here. If you are in Copenhagen and out of warranty, it is usually a same-week, fixed-price job rather than a reason to replace the machine.

When it is genuinely worth replacing instead

Honesty matters more than a booking. A clean and repaste is not always the answer.

If the machine is many years old, already throttles badly after a recent clean, and you are pushing it at work it was never built for, you may be paying to delay an upgrade you will make anyway. The same is true if a fan itself is dying — a fan with worn bearings rattles and grinds, and no amount of paste fixes a fan. A good technician tells you that before taking your money, not after. Sometimes the right answer is a single new cooler or fan; sometimes it is a fresh build. Either way you should hear it straight.

Frequently Asked Questions

Q: Why is my PC running hot all of a sudden?

A PC that is suddenly running hot is almost always a cooling problem that has been building for months, not a part that just failed. Dust packs the cooler and the thermal paste dries out over one to two years, and a hot day or a demanding game is usually what finally exposes it. A clean and repaste resolves the large majority of these.

Q: How much does it cost to clean a PC and replace thermal paste in Copenhagen?

GGFix does it at fixed prices: a 599 DKK Express Clean with a CPU repaste, or a 999 DKK Deep Clean with a full strip-down, fan service and a before/after temperature report. GPU repaste is an extra 200 DKK. No hourly rates and no surprise bills — the price is agreed before any work.

Q: How often should I clean my PC and repaste it?

For a PC used regularly, clean it every 6-12 months and repaste roughly every 2-3 years. A dusty room, carpet, or pets shorten that. If it already idles hotter than it used to or the fans are running loud, it is overdue now.

Q: Will compressed air fix an overheating PC?

It helps a little by clearing loose surface dust, but it does not reach the packed fin stack where the real blockage forms, and it does nothing for dried-out thermal paste. Compressed air is good maintenance between proper cleans, not a substitute for one.

Q: Can GGFix fix an overheating PC in Copenhagen?

Yes — cleaning, repasting and fan work is one of the most common jobs we do, at fixed prices and usually within the week. We diagnose it first so you are not paying for a clean if the real fault is power, RAM or the board, and we tell you honestly when a machine is better replaced than repaired.