They do have fans… most of the time anyway. Apple has some “unique” design philosophies when it comes to thermal performance… Which is that thermal performance is the last thing they consider, always. A good example of this is the so called “placebo fan” of a few recent MacBook Air models, here is a picture of it with the base off:
Here is a version with the expected airflow:
Now, if you are aware of normal thermal design, you would realize that normally a heat pipe runs from the heat-producing parts (CPU/GPU) to a heatsink that has a fan directly attached to it and forces air directly through the heatsink. It is done that way because it is the most efficient way of cheaply cooling the computer.
Instead of cooling the laptop in the proper manner, Apple chooses to make this abomination, which relies on static pressure generated by the fan to pull air over the CPU and its heatsink and then exhaust it from the laptop. There are a few problems with this design:
- static pressure powered flow is very sensitive to direction changes, of which there are at least two major (and many smaller) changes of direction in the normal flow
- it relies on the case being airtight enough that the vast majority of air is drawn from the far side of the laptop (which most are not).
- the VRM’s (onboard direct CPU power supplies) are uncooled
Now, this cooling solution is better than nothing… but it is probably the worst cooling solution (and most underpowered one) I have seen in a laptop. To make up for it the laptop has extremely aggressive performance curves, in that you can use the processor’s full potential for a few seconds, and then it is throttled back to a small fraction of its true performance envelope until whatever bogged it down is complete. As a result of this, the laptop runs EXTREMELY hot (as they run it right on the edge of the maximum operating temperature) and can burn itself to death or significantly reduce its lifespan.