It's hard not to like overclocking. Take a system, tweak it and it becomes faster! What's not to like?
Some components are happier being pushed than others, and testing the boundaries of overclocking usually involves slowly increasing frequencies and voltages of board and processor until it becomes uncooperative and falls over.
Often, that's because something has got all hot and bothered. If you're putting together a hot system, literally as well as figuratively, dissipating heat is key. Improving your cooling improves your overclocking potential, which means more sugary gaming goodness.
We're all familiar enough with spot cooling. To keep you processor cool, for example, you add a decent chip cooler. However it's awfully easy to get a little obsessed when it comes to spot cooling, and to totally forget where all that heat is going.
Sticking efficient coolers on your chip, memory, motherboard chipset and the rest is good practice, but all it really does is move the heat from the components to inside the case. Now you face the challenge of needing to shift that heat out of your computer and into the big wide world, or it'll all just sit inside like a cosy, yet overclock-spoiling thermal blanket of hot air.
So you simply stick an extra fan on your case right? There's a bit more to it than that. This is where the gaming cases come into play.
These have been designed with the same twisted aims that you have - to build a half-insane custom gaming rig. Do yourself a favour and start by investing in the best PC gaming case for the job first.
When the backroom boys were thrashing out the specifications for the ATX case, they didn't envisage you fitting components that amount to small electric fires inside the case. So we find ourselves in the position where the bog-standard ATX case is woefully inadequate.
A gaming case gives you room to get air moving between components and positions them for optimal flow. Plus, of course, it'll come bedecked with fans. However, new case or not, you can do a lot by simply arranging things properly inside your current case.
So, before you start thinking about lapping the bottom of your heat sink or investing in liquid gallium thermal paste, go back to basics and take a look at the cooling across the whole system. It's all about airflow and a few simple changes here and there can make a real difference with minimal investment.
Why is your PC producing so much heat anyway? Make electrons flow down a wire and the wire gets hot, and there's not a lot that can be done about that until they sort out superconductivity at room temperature. Quite simply: the more watts, the more heat.
Given big graphics cards can easily run at over 200W each, and people seem insistent on fitting two or, in extreme cases, four of the things, you can see how PCs have got all toasty inside.
Thermodynamics starts off fairly gently with specific heat capacities and thermal conductivity, and pretty soon after that its gets hideously complicated. It also involves frequent references to hot bodies, which made us all snigger quite a bit at school (actually it still does).
Every action produces heat as waste energy, which is why perpetual motion machines never work. So, high power components inevitably mean high heat levels, and unless you fancy running a system immersed in mineral oil, air-cooling is your friend.
Air is a pretty good thermal insulator - that's why double-glazing works so well. To keep transferring heat away rapidly, you need to change the air, as witnessed on cold and windy days. Wind chill doesn't actually make it colder (you can't be colder than the air temperature, assuming you are not wet, which is another story), but the wind whips away your insulation and makes it feel colder while you wonder why human evolution has deprived you of fur.
The three big generators of heat are the graphics card, processor and power supply. Graphics cards - proper heavyweight ones that interest serious gamers - are veritable little furnaces. The big boys have vents to the outside on the rear expansion plate and closed covers with input fans inside the case.
This means the internal airflow over the GPU and memory is controlled. Thanks guys! What you need to do is ensure that these fans are fed lots of cool outside air that circulates around them freely.
Here we come to the side fan - a gaming case speciality that sits over the cards and blows directly on them. Opinion is divided here - some designs make a feature of it (witness the big ducted fan of the Cooler Master HAF X), while others eschew any sideways action and run with closed sides.
The problem with side fans is that they interfere with the cross current going from front to back, leading to turbulence and air going every which way. Your best bet is to optimise the main cross flow first, and resort to side cooling if that doesn't prove sufficient.
If your graphics card doesn't vent to the outside, things are a little more difficult, since getting airflow over the card is impeded by the expansion card slots at the rear and by the card itself vertically. Fans sitting on top of the graphics card can easily circulate much of the same air. Removing expansion slot blanks can create handy extra exhaust vents.
Big gaming rigs have big power supplies. The thing to look for here is the efficiency of the supply, since what you lose in the transformation of voltages is mostly heat.
For example, drawing 400W on an 80 per cent efficiency supply means you've lost 80W in heat, on an 85 per cent supply it drops to 60W and at 90 per cent it's just 40W.
Your power supply draws air from the sides and/or front and vents it out the back. Standard ATX cases put the PSU at the top, next to another hot spot - the processor - and have it drawing air from inside the case. A gaming case moves the power supply to the bottom, well away from the processor, and more often than not there'll be a grille in the case floor to enable it to draw air directly from the outside, giving the PSU a separate airflow. Neat.
Next we have the processor, and here you need to make sure that your CPU cooler is working in cooperation with the rest of the flow. You might scoff, but it can be all too easy to mount the cooler in such a way that the fan isn't blowing in alignment with your main airflow. Gaming cases mount the motherboard at the top of the case, which means your processor is close to the top and back, where it can exhaust freely.
Hard drives can get warm too, although you need to work hard to make this much of a problem. Cases generally run the drive in a stack down the front of the case, behind the front fan. Spacing drives out helps keep them cool, and avoid stacking them all in front of your graphics card.
Fans are generally defined by two things, the size and the rotational speed. Put these two together and you come to how much air it can actually shift, measured in CFM (cubic feet per minute).
There are metric units for airflow, but PC fans largely remain imperial, although the fans sizes have gone metric. And if you think that's anachronistic, bear in mind that time and angles are measured using a system from ancient Babylon based around the number 60.
There are two ways to get more air flowing: increase the diameter of the fan or increase the speed. Fans also have efficiency levels - flow against rotational speed - and it will depend on the design of the blades exactly where the sweet spot is. Spinning faster means more airflow, although as you go faster the gains tails off and it gets noisy.
The range is huge. An 80mm fan designed for quiet running may shift 10-20CFM, while the performance monsters can run up to 80CFM. More typically, an 80mm shifts about 30CFM and a 120mm fan more than twice that. If you've got the space to spare then generally the bigger the fan the better, if only to keep things quieter.
The fan's noise level is measured in decibels - more specifically it's dB Sound Pressure Level (dB on its own isn't a unit, merely a logarithmic scale applied to other measurements). Since it's a logarithmic scale, you have to be careful when comparing numbers - small changes mean a lot.
A 20dB fan is jolly quiet, equal to the background noise in a quiet room. At 30dB it's starting to get intrusive. A typical conversation might be held at 40dB or above, and once you hit 50dB or more it's getting rather noisy - the spin cycle on a washing machine, for example.
To be both powerful and quiet is ideal, but it's generally a compromise. Read the small print on sound level, because some very high-performance fans that have huge CFM figures (200+ CFM on a 120mm fan, for example), are also incredibly noisy at 60dB and over. Nice cooling, but even with headphones they're an annoyance best left for server rooms.
Shifting lots of air about does things to the pressure, and here we come to negative- and positive-pressure cases. A positive-pressure case has a higher air pressure inside than out, because you've got more powerful intake fans than exhausts. A negative air pressure case is the other way around - too beefy an exhaust fan means the intake can't keep up and you get a drop of air pressure inside the case.
Dust is bad inside a PC case, it insulates components and clogs fans, and your PC is a veritable dust magnet. Dust loves a static charge, and your PC's innards are awash with those.
In a case with negative pressure, the air gets sucked in through every little hole around the drives and cards and everywhere else, drawing in dust. Once inside, most of it'll hang around causing trouble.
A case with even a modest positive pressure will take in air mostly through the intake fan, and air inside is blown out through all the myriad holes, helping keep dust at bay. Look for cases with mesh filters over the fans that you can clean, particularly the intake ones. Even the cleanest room has a lot of dust, and your PC acts like a little static vacuum cleaner.
Decent case cooling is all about balancing input and output and tracing the airflow path, making sure cool input air is directed over the hot spots and vented out again. Before you just start adding fans, it's worth making sure the ones you have are in the right place and are given room to work as unobstructed as possible.
Go for cross flow. Adding fans all over the shop blowing inwards can end up keeping hot air trapped inside because all the fans are working against each other. Having all the fans blowing out leads to air being sucked into the case where you possibly don't want it coming from, and it'll fill with dust.
In both cases, you've lost control of the air paths. Should you go for a positive or negative pressure system? Your call. A negative pressure system offers slightly better cooling, since air is being sucked into case from all holes all the time, keeping things moving in hard-to-get places, but it will get dirty.
Nearly all gaming cases go for positive pressure, often with considerably more input fans than output. So we'll go with that, and mesh filters please.
Top, front, side and bottom
A standard ATX case has a front input and a rear exhaust, with possibly one or two 80mm fans. Gaming cases can add a top exhaust, side input, bottom input and more, plus grilles here there and everywhere, with and without extra fans of up to 230mm.
Essentially, we have two approaches: fan-based excess and the the somewhat more sober control of airflow. Not surprisingly, cases hailing from companies also involved in flogging cooling fans tend to be covered in the things.
The Antec DF-85 has seven, while its LanBoy Air has five, and barely a solid panel on it. Cooler Master's HAF X has a more modest four, although they're all big ones. Meanwhile the Corsair 700D carries just three 140mm fans and the BitFenix Colossus Venom makes do with just two meaty ones.
Some people have experimented by running systems with various numbers of fans, and the results reveal that more is indeed not always better. One good strong flow across a board is as good, or better, then air blowing all over the shop. Having lots of fans buzzing away is reassuring and looks the business, but it's in danger of being all blow and not much cooling.
As the BitFenix case shows, mounting large input and output fans at opposite corners to a case with proper room inside and a clear airflow between the two will produce enough cooling for a decent gaming system (which means overclocking).
Right, you've looked inside your case and worked out the airflow, starting with the main front to back flow and making sure that all the fans are working in co-operation, and you've moved components about to give maximum room around each one. What else can you do?
Firstly, you can tidy the cables away. A dense, unruly tangle of wires will deflect air all over the shop, so use the cable tidies the case came with and pack them away. Gaming cases mount motherboards so you can route cables underneath them, well away from the hot bits.
Now, leave the case's side panels on. What's the point of paying attention to the airflow and then leaving off the sides so your fans' flow is dissipated to the outside, rather than being routed over your hot spots first?
Also, don't stick your system right against a wall or in the corner under the desk, either. You need to give it room to breathe. Watch the dust, too. If you suffer a thermal shutdown on a system that's been up and running for a while, check all the fans and spreaders. It really is amazing how much of the stuff can be sucked into a fan over a year.
Your best bet, though, is to start with a solid performing and properly designed case to begin with - a specialist PC gaming case, in fact. Which brings us neatly to the following choice contenders…