Water Cooling 1x1

This article illuminates the advantages of water cooling systems and provides tips for building them.


The billions of electrical circuits in a modern computer consume plenty of power - most of it is eventually dissipated as heat. A modern graphics card alone can constantly emit more than 500 Watts of thermal energy. Because the chips could literally melt at high temperatures (80-110 °C) they have to be cooled down. In most standard computers this is done by metal coolers, heatpipes and air fans. An alternative cooling solution are water cooling systems.

Advantages and Challenges

Pro Contra
very quiet, much less noise proper systems are very expensive
enables performance gains of up to 50% construction and maintenance effort
unique look failures can lead to destruction of expensive hardware
can extend the lifespan of hardware risk of warranty loss when tuning hardware components
handicraft work is fun system gets heavier and more complicated to transport

Tips and Tricks

  • Building a water cooled system requires some knowledge of how computer hardware works and fits together. If you're lacking this you'll probably end up with a big mess of broken components.
  • Be aware that building a proper system requires many hours of effort and can cost a lot of money (1000$ and more)
  • It can be very (!) difficult to fit water cooling systems into small and medium sized cases. On the contrary, many full tower cases are even prepared for water cooling systems, which makes things much easier.
  • Established and specialized vendors such as Aquacomputer, EK-Water Blocks, Heatkiller, Koolance, Phobya, MIPS or Watercool guarantee quality - don't go for the cheapest parts.
  • Plan the system on paper! You will at least need: CPU-Block, 12V pump, 2m of tubes, a radiator, corresponding fans, fittings and cooling liquid.
  • For a full fledged system you will also need a reservoir, GPU-Block(s), a Mainboard-Block, more radiator surface, a central control unit and maybe RAM and HDD coolers.
  • Apart from that there are some optional additions, for example flow meter, fluid level sensor, dedicated temperature sensors and cooling liquid colors.
  • It's recommended to use special water cooling liquid (distilled, deionized water with additives). Do not use normal tap water. Cooling liquids are available in all different colors. Colored liquids definitely add to the looks, however if spilled they may irreversibly stain/colorize clothes/furniture/floors etc. For this reason I would personally not go for colored liquids anymore.
  • The size of the radiator surface is crucial for good cooling performance in combination with quiet operation. Per watt of maximum dissipated heat you should have at least one square centimeter of radiator surface. For a 600W system (dual-GPU) two 280x140mm radiators (784 cm² total) with 1500rpm fans would be sufficient. To a certain extent, less surface can be compensated with high speed fans (~2000rpm) but that will be nearly as loud as with standard air cooling. If the radiator setup is more spacious, fans with a maximum speed of 1500rpm should be sufficient - most of the time they will run at half the speed or less.
  • The chain is as strong as its weakest link. A single low-flow component in the circuit (e.g. having a narrow inner diameter) can massively limit the flow speed and thereby the cooling performance. Therefore bottlenecks in the circuit should be avoided.
  • The common size for fitting threads is 1/4", having an inner diameter (ID) of approx. 9,3mm. There are two main types of fittings:
    • Compression Fitting: Tightened via screws and therefore user friendly and very safe. The fitting ID is usually slightly smaller (~1-2mm) than the tube ID. To avoid a bottleneck, tubes with at least 11mm ID should be used (e.g. 16/11mm).
    • Barbed Fitting: Optionally tightened via clamps and therefore less user friendly and safe. The fitting ID usually equals the tube ID. To avoid a bottleneck, tubes with at least 9,5mm ID should be used (e.g. 16/10mm).
    • Push-In Fitting: Tubes are pushed into fitting, thats it. Very user friendly but not very safe. The fitting ID is smaller than the tube ID. Not recommended.
  • Design a linear flow circuit. Even when connecting many water blocks in a row, the difference in water temperature will only be max. 5 °C. Junctions that lead to parallel circuits with differing flow resistance should bee avoided, as the flow speed might become unpredictable, resulting in bad cooling performance.
  • Provided you are building a medium to high-flow system (> 50 litres per hour), the temperature of the coolers will be pretty much the same (Δt<3°C), regardless of the order of the coolers in the flow circuit. Because of that, try to focus on short hose lengths instead of the ordered arrangement of components.
  • A combination of high heat output and small radiator surface will most likely lead to relatively high water temperature (over 40°C). In this case you should avoid using hard disk coolers because they will actually heat up the hard drives, which can lead to HDD damage.
  • Electronic water pumps vibrate with frequencies of 30 to 150 Hertz. It is strongly recommended to use elastic rubber pins or special sponges to decouple the pump from the case to reducie vibration noise. Alongside the pumps create a pretty stong magnetic field, which can influence other electronic components. In case you want to add a magnetic shielding, keep in mind that the magnetic field is just barely shielded by steel or aluminium, you should use Mu-metal (nickel-iron alloy) or normal iron.
  • The flow speed can be increased by raising the pump frequency (and thereby the noise) but exceeding more than 60 litres per hour only gives very little performance gains.
  • For very big and complex systems, it might be useful to have multiple pumps. The question of operating them in sequence or in parallel is being discussed rather controversially. Anyways I made good experiences with sequential circuits, where a second pump increased the overall throughput by around 70%.
  • Never attach any inert (motion inertia) connectors to the pump. Although the system might at first seem leak-proof, the cooling liquid might be pushed out of the junction once the pump vibrates for some time.
  • Always tighten the connectors very strongly. Otherwise it might happen, that a twist at one component might lead to a leak at another component.
  • To prevent persistent damage, some pumps (e.g. the Eheim-based ones) will forcefully poweroff the PC (by short fusing) if operated for more than 5 seconds without liquid.
  • You can choose from a variety of materials for your cooling equipment - each of them having unique advantages and disadvantages.
    Avoid mixing different metals as this leads to galvanic electric tension and thereby to disintegration of metals.
    • Copper: very good thermal conductivity, not that cheap, prone to scratches and color-change
    • Nickel-plated Copper: very good thermal conductivity, looks nice, durable, quite scratch-resistant, more expensive than pure copper
    • Silver: best possible thermal conductivity, looks nice, way too expensive
    • Aluminium: pretty cheap, quite bad thermal conductivity, slowly corrodes even when using distilled water
    • Delrin/POM (Polyoxymethylen): cheap, light, solid, no significant thermal conductivity
    • Stainless Steel: solid, scratch-resistant, looks nice, unmagnetizable, very low thermal conductivity
  • A T-link with a valve, at the top and the bottom of the liquid circuit enables easy filling and draining.
  • Advanced water cooling controllers can calculate the complete thermal emission of a system using the temperature difference before and after the radiator (using inline temperature sensors) as well as the flow rate.
  • After completing the build or after a change in the flow circuit, fill the system by only powering the pump using a discrete power adapter. Don't power the whole system, because the hardware could overheat (because of no cooling) or short-circuit (because of leakage) and get destroyed.
  • Never work on the flow circuit when the system is running. Even (dis)connecting water-tight quick-release couplings might cause severe spillage-problems due to the potentially high pressure of the cooling liquid.
  • Some parts and tools that can make building the system much easier and are therefore highly recommended:
    • Hose Clamp: enables for changes in the flow circuit without pouring the whole system
    • Thread Sealer Liquid: crucial for insulating fittings without O-rings (alternative: Teflon Tape)
    • Extension/Y-cables: enable for easy laying of cables for a tidy case

Flow Circuits

Here are some case internal flow circuits that are optimized for high cooling performance and easy filling/draining as well as transportability.

Dual Standard Radiators

This circuit is designed to fit normal Full Towers (min. inside space: 60cm long and 50cm tall) with the PSU at the bottom. It provides good cooling performance.

Dual Standard Radiator Watercooling Flow Circuit

Dual Huge Radiators

This circuit will not fit any standard case and thus may only be used in custom case constructions (casecon). This circuit is used in my casecon "Aquacube". It provides extreme cooling performance.

Dual Huge Radiator Watercooling Flow Circuit

Single Big Radiator

This circuit is designed to fit large Full Towers (min. inside space: 70cm long and 55cm tall) with the PSU at the top. It provides good cooling performance.

Single Big Radiator Watercooling Flow Circuit

Radiator Surface

The radiator surfaces of the most common radiator types. For the actual radiator size you have to add around 0-10mm in width and 20-60mm in length.

Fan Size (mm) Number of Fans Surface Dimensions (mm) Surface Area (cm²) Surface Relation (%) Max. Outer Dimensions (mm)
120 1 (Single) 120x120 144 33% 180x130
2 (Dual) 240x120 288 66% 300x130
3 (Triple) 360x120 432 100% 420x130
4 (Quad row) 480x120 576 133% 540x130
4 (Quad square) 240x240 576 133% 300x250
6 (Hex) 360x240 864 200% 420x250
9 (Nona) 360x360 1296 300% 420x370
140 1 (Single) 140x140 196 45% 200x150
2 (Dual) 280x140 392 91% 340x150
3 (Triple) 420x140 588 136% 480x150
4 (Quad row) 560x140 784 181% 620x150
4 (Quad square) 280x280 784 181% 340x250
9 (Nona) 420x420 1764 408% 480x430
180 1 (Single) 180x180 324 75% 240x190
2 (Dual) 360x180 648 150% 400x190
3 (Triple) 540x180 972 225% 580x190
4 (Quad square) 360x360 1296 300% 400x370
200 1 (Single) 200x200 400 93% 260x210
2 (Dual) 400x200 800 185% 460x210
4 (Quad square) 400x400 1600 370% 460x410
220 4 (quad square) 440x440 1936 448% 500x450

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