Function and Importance [Source]
A CPU cooler is designed to remove excess heat generated by the processor to keep it within safe operating temperatures.
A stock cooler will be provided with most processor from Intel and AMD, if you don’t want to overclock or do any intense gaming; it will be perfectly sufficient. However, if you do plan on doing so – a third party cooler is necessary.
Idle and Load are terms you’ll here often and can be explained easily, idle is the state where the processor is “at rest“, it’ll be performing essential functions and little more, like a car ticking over as you wait to set off. Load is when the processor is operating at peak, it’s dealing with all the resources it can handle and since it will draw more power, will produce more heat. However, there is a sliding scale for this and no discrete states of function but usually benchmarks will be taken during intense gaming or a program which will “stress” the CPU in order to test it.
Typically this will be based on air flow cooling, with the cooler consisting of a heatsink placed onto the top of the processor. Generally copper is used for the thermal pipes which you can see in the diagram below – these are in contact with the CPU and take the waste heat generated there and remove it, via conduction, resulting in the thermal energy being transferred to the blades. The purpose of this multi-layered structure is to provide a large surface area which can lose heat more quickly. A fan attached to the side of the heatsink draws cool air between the blades, reducing the heat build up and overall – this keeps the processor cool.
Thermal paste is necessary to fill the gap formed from imperfect surface contact between the heatsink and the processor, without it, thermal energy would not be dissipated efficiently and the processor would likely overheat under load.
This very crude diagram, yes… it was done in paint, shows the concept – with red being the thermal paste material. The quality of the paste you use will have an impact on the temperature, often dramatically.
Manufacturers will usually include paste either pre-applied or in a separate syringe. The action of application will matter also – a pea sized amount is all that is necessary combined with equal pressure on heatsink fitting and tightening.
Water Cooling [Source]
A water cooler combines a block which attaches the the CPU, via connective pipes – liquid is circulated through, taking heat produced at the processor and with the help of a pump, moves it to a radiator. With essentially the same function as the heatsink on the air coolers, the radiator will often feature a layered structure with a fan attached, helping to lose the heat built up.
Which one is better?
Well, it reverts back to money again – you can get a good air cooler for £25 which will allow for modest overclocking and still provide good temperatures. There are water coolers available for £30-40, but these solutions won’t be of high quality and when you’re using liquid, the worst thing that can go wrong is the item start to leak all over your motherboard and cause other issues; cheaper coolers will also be louder.
From what I’ve seen, water cooling isn’t cost effective unless you can afford to get a double radiator, where it’ll be leaps and bounds beyond an air cooler. However, most water coolers will be quieter, smaller in size and often much nicer to look at. Although I personally didn’t use one in my desktop build, I would certainly pay extra for it next time.
Fun Fact: The Fractal Design Kelvin S36 is £130 – with a 320mm long radiator and a triple fan construction with pure copper construction makes it one of the best available cooling solutions. [Source]
As always, when buying these parts, research well and compare reviews – sometimes unfortunately it’s down to luck, you may pay over £100 for a Corsair or NZXT double radiator that is defective and they have to send you a replacement; you may pay £60 for a top end Cooler Master v8 air and find the fan breaks after a few months. The longer the warranty the better, but as long as you dedicate enough cash to it – you should have no problems.
I have the Cooler Master Hyper 212 EVO in my desktop, at stock frequencies on the i5 6600K it provided an average idle temperature of 25°C and load temperature of 55°C. Overclocked to 4.5Ghz using 1.3V, my idle increased to 27°C and my load to 62°C. [Source]
Although I am happy with this, I have only recently experimented with overclocking and had I known more at the time, I would have opted for a more expensive item – which would probably allow me to achieve a better core clock, or at the very least, keep my load temperatures nice and chilly.
In the other build I have done, I stuck with the stock cooler as my younger brother would not be overclocking – which gives roughly the same temps at stock frequencies as my 212 EVO, on the i5 4690K.