Chylld's guide to watercooling
Watercooling is becoming ever more popular these days, no one doubts that. More and more people are coming to this forum wanting to know a bit about this and a bit about that and in general, a bit about everything to do with the phenomenon that is watercooling. I'm starting this thread in a hope that it can be used to the benefit of all users, new and old, so that we can better work towards our own (and others') quiet
I am not trying to pretend to be a watercooling god here, so I am more than welcome to suggestions so that this first post may be updated with the latest and most correct information.
Just keep in mind that we have a common goal here: silence.Overview
Watercooling can be summarised as thus:Advantages:
- lower operating temperatures
- higher overclocks
- localised hotspot management
- a potential for a quieter system
- it just damn looks cool
- packaging (i.e. fitting everything into a case!)
The benefits of watercooling arise from the fact that water is much better at taking heat energy away from a heat source than air. This gives you lower temperatures, but what's the use of this if your computer is already stable? Because it also allows you to run the fans slower, hence your system will be quieter, as well as cooler. It also allows you to overclock your processor. Think of it this way: you could buy an athlon 3200+ for AUD330 and leave it at stock speed, or you could buy an athlon 2500+ for AUD140 and overclock it to over 3200+ speeds. The overclocking headroom given to you by watercooling has saved you AUD190 in this case. This is only a rough example with estimate numbers, but you get the idea.
Watercooling also allows you to focus on removing heat from a singular source: the radiator. Airflow inside a case can be tricky to manage, as the CPU is over there and the video card is over there, etc. With watercooling, you don't need to worry about how this fan is stealing airflow from this fan, or this is obstructing that, etc. All you have to do is cool the radiator.
Because of this, you can use 1 or 2 large 120mm low-airflow fans to cool your cpu, gpu and whatever else you have plugged in to your loop. Adding a new powerful graphics card? No worries, just plug it into the loop, and you wonâ€™t have to suffer from additional noise from additional fans. If desired, turn the radiator fan speed up a tad to cover the added heat source, but thatâ€™s it. A decent radiator has more than enough cooling power to gobble up the heat from both a hot CPU as well as a hot GPU.
The main downside of course, is the cost. Your average waterblock may not cost much more than a high-end heatsink, but when you add up the cost of the pump, radiator, tubing, clamps etc it starts to look pretty messy. However, when you keep in mind the savings you can make through overclocking (as illustrated above) and also the simple fact that a watercooling system will provide adequate cooling for many system configurations to come, it turns out to be a worthwhile investment.
Maintenance, on the other hand, is a nightmare. If you want to change your cpu block for example, you can't just unmount it and whack a new one in. Instead, get a towel, lay it down and hope that it catches most of the spill, because it's going to be messy and there's little you can do to avoid it. Hose shut-off clamps help a little in this regard, but there is always going to be some liquid spilling out so you'd better be prepared!
However, spillage isn't as bad a thing as some people make it out to be. As long as you're using a good brand radiator coolant, the electrical conductivity of the coolant will be reduced to the point that you can actually have a block leaking into your system without you even knowing it. I myself had my cpu block leak onto my bare Radeon 9800 card, and it had zero effect. YMMV. And if it does stop working, people have had success by throwing the affected components in the oven at 50C for 30 minutes to an hour or so, to get the coolant out of the tricky spots, and their equipment turned out as good as new. Again, YMMV. Always take the appropriate precautions:Avoiding catastrophe:
- always use hose clamps. worm-drive / worm-gear clamps are very reliable and quite cheap too.
- leaktest the system for up to 24 hours before you turn the computer on. Note that you don't really have to do this outside the system, as long as it is off and unplugged from the wall, no ill effect will be done. Lay down some pieces of paper under various parts so that leaks can be detected easier. I recommend leaktesting inside the system, as it can be a total B#*@H to reinstall a whole watercooling system, all connected up, with only 2 hands.
- use a radiator coolant additive, pretty much any radiator coolant product at your local store will suffice. Just mix as per the product's instructions. Also, if you like glowy things, pick a coolant that is UV reactive, like what I use (Nulon Ultra Cool) so you don't have to mess around with UV dye later on.
- avoid mixing metals. ideally, you want everything to be either copper, brass or some form of plastic. while mixing aluminium together with copper in a watercooling system is not as bad as some people make it out to be, it creates a battery effect which speeds up an ugly process known as galvanic corrosion. radiator coolants help greatly in this regard, but still, avoid mixing metals where you can.
- make sure your system is properly bled, i.e. air-free. with a reservoir, this job is done automatically. with a closed-loop system, you have to get it right the first time or you're in for a noisy pump and hampered system performance.
OK, with that out of the way i'd like to have a section where answers to common questions can be read right off, so here goes.Does the order in which my system is plugged together matter?
NO. There are too many people who believe in the myth that cold water goes into the waterblock, and comes out as hot water, where it is cooled by the radiator and comes out again as cold water. This is WRONG. The flow rate of any respectable watercooling system is such that the water never changes temperature significantly in the time it spends in any one item. As such, the temperature differential between the hottest and coolest parts of the loop is next to ZERO, if not no more than a single degree celsius.
In fact, the ONLY order rule that exists is that the reservoir (if you have one in your loop) must be immediately before the pump.
So, when you're plugging up your watercooling system, the only thing you need to keep in mind is the physical bending of the tubing, which is explained in the answer to the next question:Is it OK to use 90 degree elbows in my loop?
Sometimes this is unavoidable. An example would be the tubing leading to/from the GPU waterblock, which can get tight especially in SFF or HTPC cases. However, if you can avoid it, you most definitely should! Generally speaking, watercooling performance depends on the flow rate of the coolant in the system. Elbows and really tight turns hurt flow rate more than you'd think. So when plugging your system together, pay attention to achieving the order which involves the cleanest, gentlest tube routing as this will afford you the greatest possible flow rate and thus performance.
One of the worst
places to put a 90 degree elbow is right at the inlet of the pump. A water restriction right before the pump means the pump has to work harder to move the same amount of water, possibly causing it to run less efficiently, as well as at a higher noise level. The same goes with any other restrictions, like tight bends or lengths of smaller diameter tubing. Whatever the case â€“ keep these as far away from the pump inlet as possible!Do I need a reservoir? What are the alternatives?
You do not need a reservoir; however it makes life very easy during the fill-and-bleed process. Here are some alternatives (blue = pump, water flow = in from left):
If a reservoir is too bulky to fit inside your case, or you just plain don't want one, another option is a t-line. This is ridiculously cheap to construct (a dollar, probably less) and essentially acts as a reservoir but is thinner, can be placed almost anywhere in the loop (ideally before the pump) and so doesn't intrude on case space as much as a reservoir. It is, however, harder to fill and bleed, as air bubbles are much more likely to fly straight past the t-line.
Another option is a closed-loop circuit. This has no t-line, no reservoir, none of that. Just the pump, radiator and blocks. How do you fill it? Well, you submerge the pump in a bucket of coolant (don't do this with non-submersible pumps!) and you turn the pump on. You then connect each component in series (starting from the pump's outlet), and give them a shake to get rid of the bubbles, until you get back to the pump and you make the last connection and that's that. While it can be a bit tricky (it's all done submerged!) it guarantees that there is no air in your loop (provided you've done it properly) and evaporation is not an issue at all.
A more complex solution is the 3-tap system, as is used by Swiftech in their fill-and-bleed kits. The coloured spheres in the diagram above are valves, and they let the user shut off water flow at the turn of a knob. During normal operation, the yellow and red valves are closed, whereas the green one is open, allowing water to flow through from left to right. When filling the system, the green valve is closed, and the yellow and red valves are open. Hoses are connected to the yellow and red valves, with their other ends submerged in a bottle/tank of coolant. The pump then pulls water through the red valve so it goes around the system and out the yellow valve. Once the bubbles are out of the system, the red valve is shut off, then the yellow valve is shut off, and then the green valve is opened.I've heard that a reservoir will give me better performance, is this true?
No, this is not true. In fact, the opposite is true. Let me explain why.
A lot of people think that the increased coolant volume a reservoir provides affords them lower temperatures, but this is false. The simple truth is that the system will take longer to reach equilibrium, i.e. for the water temperature to stabilise, because there is more coolant to heat up. Readings taken before this equilibrium is reached are misleading and often incorrect.
In fact, a closed-loop system gives better performance. Why? In experiments done by numerous watercooling enthusiasts (including Aussie legend Stew Forster, a.k.a. "Cathar") it was found that in a reservoir system, the pump was burdened by the task of having to accelerate still water. In a closed-loop system, the water entering the pump is already travelling at speed. Thus, the flow-rate in a closed-loop system is higher, enhancing the performance of the waterblocks and thus the overall system. Which way should I have the fans setup, sucking through the radiator or blowing onto it?
Sucking is quieter, gives better performance, and is often more space-efficient than blowing, as is explained in the "Shrouds" section below. Sometimes, however, your case configuration forces you to use a 'blow' setup, but it's not that bad, so there's no need to cry over it.
The concept that sucking air through a radiator is more efficient takes some getting used to, especially since aircooling usually involves blowing air onto a heatsink. The critical thing to remember is, weâ€™re not blowing air onto
the object (as we do with heatsinks) but instead, weâ€™re trying to pull air through
it. With axial fans, pulling/sucking is the most efficient way to do so.Why should I bother getting a better pump? How will higher flow rates benefit my system?
want a greater flow rate in your system. Higher flow rates create more turbulence, which leads to more efficient heat transfer. Higher flow rates also help to break through what is known as a â€˜stagnantâ€™ layer of water between the coolant flow and the surfaces of the waterblocks themselves. This is especially true for impingement blocks which rely on jet impingement effects to effectively transfer heat from the heat source.However,
this does NOT mean that you should just go and get the best pump out there. Pumps dump a significant amount of heat into the loop, and more powerful pumps dump more heat than less powerful pumps of the same type/brand. For open impeller centrifugal pumps like the Eheims, a doubling of pumping power (e.g. Eheim 1048 -> Eheim 1250) will only increase the real-world flow rate by about 25%, which in turn only improves the performance of the waterblocks by around 0.01 C/W (temperature rise (in Celsius) per power unit (Watt) produced by the CPU). On a CPU in the 100W region (i.e. a very hot overclocked CPU) the temperature improvement would be 0.01 x 100 = 1 degree Celsius. However,
when you add the extra pump heat into the equation this benefit is greatly nullified, especially if your radiator setup isnâ€™t particularly top-notch.Component choice advice
Now onto what is undoubtedly a touchy subject - choosing components. Instead of suggesting particular components, I'm going to try to keep things as general as possible, keeping in mind the fact that silence is our primary focus.Waterblocks
Unless you are aiming for major overclocks, you do not need a fancy waterblock. However, this does not mean that because you don't have the best pump, you can't
get so-and-so high performance waterblock that performs best with high performance pumps. What a lot of people don't realise is that these high performance waterblocks outperform the average waterblocks even at low flow rates
. So if cost is not an option, get the best block you can buy.Radiators
Stay away from retail watercooling radiator offerings, such as the Black Ice series. These may perform okay-ish, but the reason I suggest you stay away from these is the price. These items are SEVERELY marked up and are out there to earn an easy buck (or a hundred) out of unknowing consumers. The fact is, you can buy a BETTER radiator for less than HALF the price at your local radiator repair place / wreckers.
A lot of people simply overlook the fact that once you watercool your computer, you essentially have the same system in your case as you do in your car. Coolant is pumped through a hot thing (engine, waterblock) and is cooled by a radiator with fans blowing onto it. Now, a car engine radiator is obviously too big for a casual watercooling enthusiast, so what you want is the car's heatercore
. This is essentially a smaller radiator that is mounted in the car, just behind the dash, and is plumbed in parallel with the car's big radiator. When you turn your car's heater on, it turns on the fans that blow air through this heatercore and into your car's cabin. (A neat trick is, if your engine is overheating, simply turn your heater on at full blast and your engine will thank you.)
Also, most heatercores have denser fins than commercial watercooling radiators, and so offer better performance for the same core area.
OK, so youâ€™ve decided on a heatercore, you have a few radiator repair places jotted down, itâ€™s time to head out and meet some quite interesting people
Now the heatercores that come from cars are often suited to tubing larger than you want, for example the popular Camry sv21 (a.k.a. â€œBig Arseâ€