XCPUs Guide to Watercooling

Overall Score

Don’t pretend you haven’t thought about it. We all have at one point or another. The sultry sound of bubbling water in a reservoir…the curvaceous allure of tubing sprawled about the interior of the case. That turn you on? If it does, read on. If it doesn’t….read on anyway, hopefully it will start to at some point.

Watercooling is a method of using water as a partial replacement for air cooling. There are a few reasons why water is so much better than air as a heat conductor (science alert!!):

  1. Water has a much higher specific heat than air. Specific heat refers to the amount of energy needed to raise the temperature of a substance by one degree. Without delving too much into the science behind it, it means that water can absorb more heat energy before its own temperature is raised, which makes it much better than air for keeping stuff like your CPU cool.
  2. More surface area means there’s a larger area for heat to leave your cooling device of choice. A trend we’ve seen with air cooling is that the heatsinks have gotten huge, and it’s all due to surface area. The beauty of watercooling (besides the obvious visual appeal :D) is that you can have MUCH more surface area for heat dissipation.

Putting these two important facts together, watercooling works on the principle of removing as much heat as it is absorbing.

This article will try to steer clear of heavy science topics where possible – this is meant to be a practical guide for people just starting out with watercooling. This guide will include parts recommendations, tutorials for constructing, draining, and filling the loop, and some galleries of XCPU users with some water setups that may inspire you to greatness…or in this case wetness.

Excellent question…one that could potentially save you a few hundred dollars. It’s hard to say whether you need to be on water or not. There are so many reasons to watercool that it’d be next to impossible to list them all here. A good majority of the time people watercool for the lower temperatures. Many times, it’s possible to maintain reasonable temperatures at high speeds by simply using faster fans. Many common air coolers like the Ultra-120 Extreme from Thermalright perform quite well using two fans in push-pull and/or higher-speed fans.

However, there’s always a limit. The new Core i7 CPUs from Intel are known to run quite warm at high clock speeds, particularly with Hyperthreading enabled. Compare that to a Wolfdale, and there’s a BIG difference in heat production. If you plan on running a Wolfdale at 4GHz water generally isn’t required – any high-end air cooler should be able to handle the heat load. An i7, Kentsfield or in some cases a Yorkfield at 4GHz however will often benefit from water and (especially for the Kentsfield) may be necessary.

Another major benefit to switching to water is reducing noise. Depending on the amount of radiator space used (more on that later) you will usually be able to run lower-speed fans to get the same or better temps.

The best way to decide if you need watercooling is to be honest with yourself. Remember, it’s potentially a lot of money to be wasted if this isn’t the best fit for you. And it’s up to you and you alone to decide if the expense and hassle is worth the gain.

There are a few basic parts that every watercooling loop needs:

The Waterblock 

First off, you need a waterblock. Think of the waterblock as the base of a standard air cooling heatsink, it sits on the processor and is the initial heat transfer layer. The waterblock may not be as important a choice as you may think, in the midrange to high-end sector at least. Realistically speaking, the high-end waterblocks generally perform very close to each other, depending on the loop with which they are being used. For a thorough review on three of the top-end blocks commonly sold today, see this review by our own Kris Wandall. As you can see, not more than a few degrees separates the three of them.

Some waterblocks do better with more powerful pumps, like the super-restrictive EK Supreme. It is often recommended that with such restrictive blocks that users put them in their own loop or use two pumps (more on that later) Other blocks, like the Apogee GT, don’t seem to care too much about the pump or the other blocks in the loop.

Restrictive Blocks:

  • EK Supreme
  • Swiftech Storm
  • Koolance CPU-350
  • Heatkiller CPU Rev 3.0

Moderately Restrictive Blocks:

  • Swiftech Apogee GTZ
  • Swiftech Apogee GTX
  • D-Tek Fuzion v2 (with quad plate installed)
  • EK Supreme LT

Unrestrictive Blocks:

  • Enzotech Sapphire Rev. A
  • Swiftech Apogee GT
  • EK Supreme (with no accelerator plate installed)

 

The Radiator

The radiator is arguably the most complicated choice you can make concerning a new watercooling loop. There are many variables to consider when shopping for radiators, such as how you plan to mount them. Are you willing to mount rads externally or do they have to be internal? If they can be mounted to the outside of the chassis, it widens the range of cases that can house a watercooling system. Radiators take up the most space of any individual part in the system, sometimes by a lot.

The next consideration in radiator shopping is what you plan to watercool. Many veteran watercoolers determine the total rad space for the entire computer they need by totaling up what each CPU and GPU needs. This is much of where the justification of expense talked about on the previous page comes into effect.

For moderate overclocks on Conroe, Yorkfield, and Kentsfield CPUs, it is recommended to have at least 240mm of radiator space. Wolfdale CPUs will usually get high clocks on 240mm, and will sometimes see their maximum clocks as well. Core i7 with HT enabled at stock will often max out a 240mm radiator, so if overclocking i7 is your goal it is recommended to go no smaller than a 320mm radiator. GPUs can usually get away with less than 240mm radiators with moderate overclocking, even GPUs like the GTX 280 and 295, or older coffeemakers like the HD2900XT.

For example, if you have a Q6600 and a 9800GTX, a 360mm single-thickness radiator is recommended. If you have an i7 920 and a 9800GTX, two 240mm radiators or a 360mm and a 120mm will suffice.

 

The Pump

The pump could be considered the heart of your loop – it’s the muscle that forces coolant through the blocks, rads, and tubing the same way the heart circulates blood through your body. Most modern PC pumps use a magnetically-driven impeller, which makes them quiet and more reliable. The pump is a surprisingly easy choice to make when building your water loop, mostly because the most popular ones perform the same. The two most commonly-used watercooling pumps are made by Laing, and they are known as the D5 and the DDC.

The Laing D5/Swiftech MCP655

You may have seen these pumps take many different names. Other companies buy Laing pumps and rebrand them to sell as their own- Swiftech’s are the most popular. The Swiftech variant is known as the D5. There is another model of D5 available from Swiftech you may have seen called the D5 Vario – the only change is a flow speed adjustment which has been shown to do very little for performance even in highly restrictive loops – so getting the Vario really isn’t required. You may have also seen the Laing D4 or Swiftech MCP650 around the Internet – this is, as the number suggests, the model that came before the D5. Performance is on par with the D5/MCP655, but is much noisier. If you can find one for significantly cheaper than the D5 and don’t mind a much louder pump, by all means take the D4.

The Laing DDC/Swiftech MCP355

The DDC is a little more complicated of a beast. Laing has released many versions of the DDC pump, the most commonly sold today being the DDC-3.2. The differences between the versions are pretty minimal, so in all honesty it doesn’t matter too much which one you get. What does matter is the wattage of the pump. It is more difficult to tell which wattage you get when you buy a Laing-branded DDC pump – most of them will be 18w. If you buy the Swiftech version, however, the MCP355 is the 18w version and the MCP350 is a 9w pump. It is recommended to buy the 18w pump unless the 9w is significantly cheaper and you don’t plan on running a high-restriction loop. The 350 is generally easier to find anyway.

 

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