Resource Cheatsheet
A+ Core 1 3.5: Cooling
A+ Core 1 3.5 — fans and airflow, passive cooling, heat sinks, thermal paste vs pads, and liquid cooling.
- Updated
- Reading time
- 3 min read
- Detail
- A+ Core 1
- Detail
- Cooling
On this page
In one line: move heat out with airflow and fans, spread it with finned heat sinks (bonded by thermal paste or a pad), go fanless for silence, or use liquid cooling for hot/overclocked builds.
Companion to: Professor Messer A+ Core 1 (220-1201), Section 3, objective 3.5. The full version is the Cooling class notes; the section overview is the Section 3 sheet.
Cooling methods
| Method | What / when |
|---|---|
| Airflow | Cool air in one side, hot out the other; keep cables clear |
| Case fans | 80 / 120 / 200 mm, often variable speed (faster = louder) |
| Card fans | On larger cards (high-end GPUs) |
| Passive (fanless) | Silent — set-top boxes, media servers, appliances; uses a heat sink |
| Heat sink | Fins increase surface area; air carries heat off (gets very hot — burn risk) |
| Liquid cooling | Block on CPU → pipes → radiator + fans → coolant loop; high-end/gaming/overclocking |
Thermal interface material
| Thermal paste | Thermal pad | |
|---|---|---|
| Also called | Thermal/conductive grease | — |
| Amount | Pea-sized (spreads under pressure) | Pre-cut pad |
| Effectiveness | Best | Slightly less |
| Mess/leak | Can squeeze out | Cleaner, no leak |
| Reusable? | No | No |
- Not an adhesive: paste fills gaps for heat transfer; the heat sink is held by clips/brackets, not glued. (Separate “thermal adhesive” does bond.)
- Beyond scope: most paste is electrically non-conductive; liquid-metal paste is conductive and can short parts.
The CPU stack
Fan -> Heat sink -> Thermal paste/pad -> CPU
(top) (bottom, hot part)🔐 Security notes
- Cooling = availability: a failed fan/pump, dust, or dried paste causes thermal throttling/shutdown (self-inflicted DoS) and can mask or mimic compromise — monitor temps (BIOS sensors/OS tools) to tell a cooling fault from an attack.
- Fans/heat are covert channels: on air-gapped machines, data can leak via fan speed/noise (Fansmitter) or temperature (BitWhisper) — niche but real.
- Data-centre HVAC is attack surface: interfering with cooling downs systems without touching them.
Practice drills
1. How does airflow cool a case?
Cool air in one side, over the warm components, hot air out the other — keep cables/clutter out of the path.
2. Three common case-fan sizes?
80 mm, 120 mm and 200 mm.
3. What is passive cooling and where does it suit?
Fanless cooling (with a heat sink) — silent, for set-top boxes, media servers and appliances.
4. How does a heat sink work?
It spreads heat over fins to increase surface area; passing air carries the heat away.
5. How much thermal paste, and is it reusable?
A pea-sized blob (it spreads under the heat sink); not reusable — replace it when you remove the heat sink.
6. When would you use a thermal pad instead of paste?
When worried about paste leaking onto other components — pads are cleaner but slightly less effective (also single-use).
7. What is in a liquid cooling loop, and when is it used?
A block on the CPU, pipes, a radiator with fans, and a coolant loop — for high-end, gaming and overclocked systems.
Key takeaways
- Airflow + fans are the baseline; card fans on big GPUs; case fans 80/120/200 mm, variable speed (noise trade-off).
- Passive = silent (heat sink, appliances); heat sinks spread heat over fins — and get hot.
- Paste (pea-sized, single-use, not glue) vs pad (cleaner, no leak, slightly weaker).
- Stack: CPU → paste/pad → heat sink → fan. Liquid cooling for hot/overclocked builds.
- Security: cooling failure = DoS that can mimic compromise — monitor temperatures.