A heat sink is a passive block of metal, usually copper, aluminum, or a mix of both, that sits on top of a CPU or GPU and pulls heat away from the chip through direct contact. It does not cool anything on its own — it just moves heat from a small, hot surface (the chip die) to a much larger surface (the fins), where a fan or ambient airflow can carry that heat out of the case. Every cooling solution in a PC, from the cheapest stock cooler to a custom liquid loop, relies on a heat sink somewhere in the chain.
What changed in 2026
- Vapor chamber heat sinks became common on mid-range GPUs, not just flagship cards. A vapor chamber spreads heat across the base more evenly than solid copper before it reaches the fins.
- Stock coolers got slightly better on mainstream CPUs as chipmakers responded to higher default power limits, but they still trail even budget aftermarket air coolers under sustained load.
- Direct-die and thinner IHS designs on some enthusiast chips reduced the distance heat has to travel before it reaches the heat sink base, shifting more of the cooling burden onto fin design and airflow.
How a heat sink actually works
Heat moves from the chip into the heat sink base through conduction — this is where thermal paste matters, because even microscopic air gaps between the chip and the base slow that transfer dramatically. From the base, heat spreads into the fins, which exist purely to maximize surface area. More surface area exposed to moving air means more heat leaves per second. This is why a heat sink with dense, thin fins and a fan moving real airflow outperforms a heavy block with poor fin design.
Heat sink materials compared
| Material |
Thermal conductivity |
Cost |
Common use |
| Aluminum |
Good |
Low |
Stock coolers, budget towers |
| Copper |
Excellent |
Higher |
Base plates, heat pipes |
| Copper base + aluminum fins |
Very good |
Mid |
Most aftermarket air coolers |
| Vapor chamber |
Excellent, more even spread |
High |
GPU coolers, premium CPU coolers |
Pure copper conducts heat better than aluminum, but it is heavier and more expensive, so most coolers use copper only where it matters most — the base plate and heat pipes — and aluminum for the fin stack where weight and cost matter more than raw conductivity.
Heat sink vs other cooling methods
A heat sink is the foundation, not a competing option, for air cooling and most liquid cooling. In an air cooler, the heat sink fins sit directly in the airflow path. In a liquid loop, the "heat sink" role is split: a cold plate pulls heat from the chip into the liquid, and a separate radiator (itself a kind of heat sink) dumps that heat into air pushed by fans. If you are deciding between the two approaches, see our guide on liquid cooling vs air cooling for the tradeoffs.
Choosing a heat sink for your build
- Match it to your case clearance. Tall tower coolers can be 160mm or more; check your case specs before buying.
- Check RAM and motherboard clearance, especially with low-profile memory or tall heat spreaders.
- Do not oversize for the chip. A massive cooler on a low-power chip is not wrong, just unnecessary spend better used elsewhere.
- Pair it with good case airflow. A great heat sink in a poorly ventilated case still runs hot; see our case airflow guide for layout basics.
FAQ
Do I need thermal paste with a heat sink?
Yes, always. Thermal paste fills the microscopic gaps between the chip surface and the heat sink base that would otherwise trap insulating air. See our thermal paste guide for application tips.
Is a bigger heat sink always better?
Generally, more surface area and more fin density help, but only if airflow through the fins keeps pace. A huge heat sink starved of airflow underperforms a smaller one with a strong fan.
How long does a heat sink last?
The metal itself effectively lasts forever. What degrades over years is the thermal paste beneath it and dust buildup in the fins, both of which are fixable with cleaning and a repaste.
Can a heat sink fail?
Not in the traditional sense since it has no moving parts, but heat pipes can occasionally lose effectiveness if damaged, and warped bases can reduce contact quality over time.
Where to go next