Water Cooling Choices

SUMMARY: I’m interested in watercooling but can’t decide what to do….

We get a fair amount of mail lately from people interested in watercooling CPUs and GPUs but they are new to it and somewhat bewildered by the choices. We’ve posted some material on various aspects of watercooling, but what I thought I’d do is give an overview of what options are available and why you might want one way to go one way vs. another.

The first question you ask is “Why do you want watercooling?”

The most frequent response I get on this is NOISE. Aircooling cases, GPUs and CPUs radiating something like 150 to 200 watts is no easy task, and consequently heatsinks have been getting larger for both CPUs and GPUS, use composite materials (Al and Cu or all copper) and the number of high energy fans has been increasing with progressively louder noise levels.

Air is NOT a very good medium for “serious” cooling, given the constraints of common materials used in heatsinks, required foot prints and form factors. At some point, more esoteric materials will make an entrance, but until costs comedown by some orders of magnitude, this is not going to happen near term.

Water is more efficient and more complex. The car analogy is simple – the aircooled VW vs. just about all others. Air is OK to a point, but water carries the day by far. But now you have pumps, radiators, hoses, hose clamps and radiator fans – lots more stuff to go wrong, but the price for efficient cooling.

Everything you basically have for car cooling you’ll have for CPU/GPU cooling:

  • Waterpump
  • Radiator with fans (fans could be optional)
  • Heat Transfer – in our case, waterblocks
  • Reservoir (optional)
  • Tubing

The MAJOR difference between car cooling and CPU/GPU cooling is that the amount of heat dissipated in comparison is trivial – watercooled PC systems do NOT get hot (hot >100C). Water temps about 5 – 10 C over ambient are typical. In addition, depending on the pump, pressures are on the low side. All of this is good news for CPU cooling, in that conditions are not extreme so that esoteric gear is not required.

OK, so what IS required? I think a good watercooling system has the following attributes:

  • Waterpump rated at least 300 gph, two year warranty
  • Copper base waterblocks
  • Tubing of at least ¼” Inside Diameter
  • Mounting for P4 and Socket A
  • Compact reservoir mounted to pump
  • Radiator at least 5″ x 5″, 3/8″ ID tubes, with 120mm fan

The “Nice to Haves”:

  • Temperature Probe in waterblock base
  • Fail safe hardware shutdown switch
  • Relay to turn AC waterpump on with PC
  • Quick-Connect fittings for tubing

First Choice: Kit vs DIY

Go HERE for a good discussion on the merits of each choice. Basically, if your objective is noise control, a top tanked kit will do the job. You have to decide whether or not you are comfortable modifying a case or not – some kits require no case modification, either because the radiator can mount in an exhaust port of the whole kit is external.

If space is not an issue, a good external kit is the easiest way to go. The Koolance external unit is capable of mounting on top of a case, and in that instance it’s more like a “built-in” than other external kits.

If your objective is performance, then DIY is definitely the way to go. Not that there aren’t good performance kits, but as your quest for “more” increases, there’s no doubt that you will be aggressively modifying your rig over time. You will wind up replacing gear, so might as well jump into DIY.


The plain fact is that the difference among well made kits and DIY gear is not that great. Water, the efficient cooling medium that it is, is a great performance equalizer.

For example, if you go HERE and look closely at Bill Adams’ waterblock tests, you will find that the difference among blocks tested is only 7 C for 100 watts radiated heat. Note that these are all well designed waterblocks; if you check the Kit Rankings, you’ll see a much wider spread. However, note that the difference among top rated kits is not all that great either – the difference among the top ten is only 9 C.

These rankings are based on a simulated CPU running flat out – in average use, your CPU is running nowhere near that, so that the performance difference you may see will not vary too much among top rated gear.

As the watercooling market continues to mature, differences will focus more on features than performance.

How Do I Choose?

I would use the following criteria:

  • Performance: 5-10 C over ambient.
  • Low Noise: Substituting a noisy watercooling system for noisy aircooling makes no sense to me.
  • Budget: $100 – 150 complete (CPU waterblock only).
  • Ease of Installation: The more you have to “fuss and adjust”, the less likely you’ll be satisfied.

What Do You Recommend?

An impossible question – new gear shows up almost every week, and what tickles me is most likely different from your taste. By if you key in on performance first, you’ll cut out at least half the kits that are out there.

I strongly suggest the following approach:

  1. Define Your Objectives: How important is noise vs performance? Are you willing to aggressively modify your case or not?
  2. Set a Budget: This will limit your choices.
  3. Research: Not only read reviews, but learn the watercooling “basics” so you can better understand the design tradeoffs of one approach vs another.

There is no substitute for knowing what you’re getting into – the more effort you put into pre-purchase research, the happier you will be with your entry into watercooling. This IS NOT rocket science – the basics are easy to grasp. Our Forum is also a great place to read and ask questions – drop by!

Email Joe

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