Cooling - A Guide

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Good review of cooling principles — Maximus Nickus

I wrote this article back in the Forum (also read comments), but for those of
you who haven’t joined up, here it is for everyone to benefit from:

Now every time I visit the Overclocker’s Forum, I see many questions of cooling; all of them are simple, if you know what you are doing – but if you don’t – then it’s a nightmare!

That is why I thought I would compile all the information I have on Air
Cooling, Watercooling and some Peltier information and wrap it into one guide. This guide is designed to be easy reading, but don’t be fooled – it will be useful for even the most seemingly perfectly cooled rig. On with the info!

Air – The Basics

The basic theory behind any cooling is to remove hot air particles and
draw cooler air particles in. This is normally achieved by exhausting the hot air out of the back and tops of the case and drawing cooler air in through the front. However there are many variations on this. Now that I’ve explained the basic principal, let’s get on with it.

Air Intake and Vents

Anyone can stick a fan into the front of a case, but positioning it to
be effective is rather tricky. Most vents in the front of PC’s have grills
over them – this not only creates a whining noise with high power fans, but it also reduces airflow by as much as 65%.

Simple one this is though: Simply take a pair of pliers and go around
the edges till it falls out. Once it’s removed, you can sand down the
edges (Careful, the edges are very sharp!) but you cannot see it from the outside, so it may not be worth the extra work of stripping down the case.

Now every front intake is positioned differently, whether it’s
right at the bottom or in a drive-cage, it all makes a difference on airflow characteristics as well as which sort of fan you should use.

Hence if there is only one intake, you will want to make the most of it.
You could either cut a 120mm intake with a Dremel or simply use a high power 80mm fan. Depending on where it is placed can also affect this decision. If the fan is blowing directly on your CPU, you may wish
to use a slightly more potent fan than originally intended to provide that
“extra” bit of airflow.

Another concern is Dust: Regardless of case pressure (explained later), dust will accumulate. It acts as an insulator, causes less and less
air to circulate through the PC and is a mammoth task to clear up. So what are the solutions?

Basically, I would use a homemade dust guard – something like a stocking
(Yes I know, no funny thoughts please!) – placing this at the front of the case, either in front or behind the intakes (depending on which is more accessible for cleaning). This will trap the dust but still maintain good airflow. Obviously you want a compromise between air and dust, so try out different combinations and monitor your temperatures.

Every system puts out different amounts of heat in different places, so
it’s really trial and error to get the best setup for your rig – just be patient and DON’T rush things.

A great tip to maximize the use of airflow in your case is to do the following:

You will need 1 sheet of see-through glass or plastic the size of your
case panel, and 1 incense stick.

Simply replace the side of your case with the sheet of plastic/glass
and put the incense stick in front of the PC (not too close – do I smell
burning?) and watch the smoke move around your PC. This allows you to see
“hot-spots” and other problems with your airflow.

Exhausts

There are many types of exhaust fans, from regular fans to PCI card
blowers. They are all designed with one thing in mind but are used for
slightly different effects.

One thing to remember is the positioning of your exhausts: You want
them as near as parallel to the intakes as possible to enable the most
efficient airflow without any blockages. A common mistake is to put them in a cluttered area where they cannot “breathe” – this causes very little
airflow and makes that distinct whining sound.

I would position a PCI slot blower under the AGP card (if there are
none available, fan apertures) coupled with a exhaust under and above the PSU; this should provide steady airflow.

Now, remember those good old science classes when you were taught
about convection, radiation and conduction? Remember how hot air particles
rise? Then there is no point in fighting gravity (who would win?), so
exhausts at the upper level of the case are very effective at removing
“hot spots” (spots around crowded areas usually in the tops of cases, and around the PSU cables where the temp steadily increases with the absence of airflow) and exhausting hot air.
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Nick Cade-Westcombe aka Maximus Nickus
Senior Member, Overclockers.com Forum

NOTE: The views expressed herein are those of the author, an independent contributor, and not those of Overclockers.com or its staff.

Pressures

When building an effective cooling system, you have to take into account
the effect pressure has on a case. Positive pressure (more airflow entering) will create a pressure of cool air and less dust will accumulate; however negative pressure (more airflow exhausting) will be exhausting more air than is available and thus, as a result, increase the dust level.

Therefore positive pressure is often the most preferred.

To achieve this simply have more air arriving than leaving!

Cables / Stopping Blockage

Every case has problems with cables travelling into the flow of the
air; this is an especially potent problem in Midi Cases.

The biggest problem is the IDE cables – they sit right in front of the
intakes and they don’t bend very easily. I decided to buy some rounded
cables however you can make your own.

My technique for clearing up the airflow is to keep all the cables
around the edges of the case using cables ties (over 100! :rolleyes: ). Basically every case is different, so experiment with different configurations (e.g. I tied my huge ATX power connector to a static plate mounted under my PSU).

Water Cooling (H2O) – The “New” Innovation

Water Cooling is rapidly emerging as the best option for high performance
cooling solutions – it provides superior cooling at a near silent noise level. While watercooling electronics has been around for a long time, its use at the PC level is just now going main-stream.

The theory behind the performance of water cooling is water’s greater ability to absorb and dissipate heat compared to air – it also is readily available (I hope so!!).

Every setup is different, but there are some principles to remember: One
is use Water Wetter! It protects components from corrosion and bacteria build up.

The next is not always to buy kits – I have saved a lot of money by buying things separately.

There are two main watercooling systems, inline and reservoir.

Inline is where there is no reservoir in the
system, just pump > pipes > Waterblock. The alternative setup is when a reservoir holds the water (no bleeding to rid the system of air needed) and it simply flows around the pipes when turned on. Reservoirs should be air and water tight.

The heart of a Watercooling system is the Pump. The things to remember are to use quiet, good quality pumps (Aquavia and Eheim pumps are very good).

As for the pump, you don’t always need to look at the GPH reading (Gallons per Hour) reading. You need to know how much pressure it can put out. It’s no use if it reads 400GPH but it’s only attainable with no back pressure!!

I always go for 3/8″ fittings so there is more water to go around, thus
equalling better cooling. However, this also leads to a drop in overall flow, so a more powerful pump is required.

One half inch fittings have less cooling capability but provide a higher flowrate, so it’s more efficient for less powerful pumps. The only time this rule doesn’t apply is with HeaterCores, as they are designed so that whatever fitting is used it won’t affect its cooling performance.

Next is the Waterblock.

There are many types, but I’d always recommend Copper. I have found that the Danger Den Maze 3 waterblock is a very hot competitor and so is the Gemini block. The Maze 3 can be found here and for a roundup of all the latest blocks look at Hoot’s article.

Some things to watch with waterblocks is how they are made. You would preferably want a solid block and maybe have it tarnish coated (like the ones from BeCooling). I also recommend lapping your new Waterblock; copper is soft and doesn’t take much effort to lap (If you don’t know what I’m talking about, either ask me or look for a guide).

Now there are new breeds of Waterblocks; these are Direct Die (fluid injection) systems which don’t have a bottom to them – the water flows directly over the core. They sound great in theory, as there’s no metal to slow down heat transfer, but in real world circumstances this isn’t always better.

Although water can disperse heat easily and can hold a lot of
heat, its getting the heat into it which is the key. Waterblocks act as heat spreaders and use a lot of technology, such as turbulence, to increase the transfer of heat into the water, thus equalling better cooling. So remember to read a few reviews about the products first.

Also they are much more prone to leaks and are a lot harder to set up. “The overclocker’s” CPU went porous which broke his CPU, so don’t say I didn’t warn you.

After you have chosen a block, you have to choose a clamp. I use the motherboard hole mounted clamp systems, but there are screwdown solutions using all six socket lugs, so pick whichever you fancy. Generally, the hole mounting system is much more difficult to attach (requires removal of
Motherboard) but they are more secure.
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Nick Cade-Westcombe aka Maximus Nickus
Senior Member, Overclockers.com Forum

NOTE: The views expressed herein are those of the author, an independent contributor, and not those of Overclockers.com or its staff.

Radiator/Heatercore

Heatercores are found in most automobiles but are rather huge and not as smart (although they are cheaper and offer great performance). I personally went for this Heatercore as its small, smart and cheap, combining the good properties of each! (Remember to test for leaks on a Heatercore out of a Car/Van.)

The Black Ice/DangerDen Supercube radiators are all superb options as well, it just depends on the severity of cooling you want. Check the amount of watts the radiator can disperse and check how many watts your
rig puts out for a rough guide.

Now the extras – first fans: You need a fan to disperse the heat collected by the radiator. I find that two 65/85CFM 120MM fans are ample
and nearly silent. You may also consider getting a shroud which covers your radiator so the fan can pull/push as much air through as possible.

Tubing: I go for Silicon Surgical tubing as it is strong, tough,
and durable, plus it returns to its original shape. It is also kink-proof in 80% of cases. But it’s your decision so choose wisely.

Clamps can be used to hold the tubing on tight, but generally speaking it’s held on tight enough by itself! It takes a lot of effort to pull it off, so they’re not really necessary, although I use them for peace of mind.

Now let’s go a bit more advanced. Say you want to cool your GPU (Graphical Processing Unit) and maybe your Northbridge as well; well, here’s some info.

Again spend the extra $$$ on copper blocks – they provide superb cooling
potential. Usually people run watercooling in series, so that’s:
CPU > GPU > Northbridge.

Now running in Parallel would be much more efficient.

So Y-Split > (1st Pipe = CPU/> 2nd Pipe = GPU) > Y-Split to
connect them back together.

The reason for this is every component (CPU and GPU alike) are getting
fresh water instead of getting the heated water from the other component.
However the downside of this is requiring a pump of 300GPH or better and also you NEED 3/8″ fittings, otherwise there will be hardly any H20.

Now if you also have a Northbridge to cool, simply put it in series
BEFORE THE GPU, as they don’t generate much heat. The GPU won’t be
heated up at all, whereas if the GPU was first in series, the Northbridge would be heated.

This is a simply Watercooling Guide, but if I have missed anything, then
please email me and let me know – also email with any questions you have whatsoever and I’ll be happy to help.

Peltiers

Peltiers work by moving the heat from one side of a plate to another, creating a temperature differential – they are solid state heatpumps. The only disadvantage is the hot side gets very hot, thus it will require LOTS of cooling – a water cooling system is much preferred to air!!

Peltiers are useful to reach a much higher overclock, as sub-zero temperatures are possible, especially if your CPU is on its edge.

One downside to this is that Peltiers require very high current to run – thus a separate power supply is often needed just to power them. Condensation is also a drawback – may CPUs have been ruined by water condensation and with refrigeration systems arriving pre-setup (although costing much more), peltiers can be a daunting task.

Useful Links

Great
prices on Water Cooling setups.

Great variety of Water Blocks.

The very best in water block technology

This guide should be of use to beginners through to experts. I haven’t been able to cover water cooling in a way I would like to, but as explained, I will when my own H2O kit arrives. Peltier and refrigeration I am non-experienced with, so I have included little information.

If anyone wishes to add to this guide then please do. When I get permission from the authors, I will be posting some illustrations also.

Good Luck with your future cooling endeavors!

Nick Cade-Westcombe aka Maximus Nickus
Senior Member, Overclockers.com Forum

NOTE: The views expressed herein are those of the author, an independent contributor, and not those of Overclockers.com or its staff.

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