For a lot of enthusiasts, a full custom watercooling (or liquid cooling, if you prefer) can be essentially the final frontier. Closed loop coolers have been taking off in a big way, bringing watercooling to the masses, but sacrifices are made in the process. The overwhelming majority of closed loop coolers employ aluminum radiators instead of the copper and brass that are used in custom loops, and the pumps tend to be on the weaker side, presumably to both keep noise down and because there's really only one component to cool. I'm still enthusiastic about these products because they can offer excellent cooling performance without placing the undue strain on the motherboard that a heavy tower air cooler can, and they're typically a win for system integrators who don't want to risk shipping damage. Whether you like it or not, this is the direction the market is heading, although pure air cooling most definitely still has its place.

So why look at watercooling? First, establish how important noise is to you. Watercooling systems (and this includes CLCs) occupy an interesting middle ground. For pure thermal-to-noise efficiency, they're basically unbeatable, but if you want absolute or near absolute silence, you actually have to go back to conventional air cooling. The reason is that watercooling necessitates using a water pump, and while they can be tuned down for efficiency, they're never going to be dead silent. An air cooler will always be a fan plus heatsink; watercooling adds a pump.

Watercooling is so efficient because it effectively allows you to spread your system's heat load across a tremendously greater surface area. Water transfers heat exceptionally well, and radiators in turn will be massive, densely packed arrays of copper fins. By being able to spread that heat across one or multiple radiators, you also allow yourself to use multiple fans at low speeds. Alternatively, you substantially increase your system's heat capacity, so if you're looking to overclock a little more aggressively, watercooling may be the way to go.

In my opinion, one of the biggest reasons to go for it is actually the potential for watercooling graphics cards, especially in a multi-GPU setup. While the stock blower cooler for the NVIDIA GeForce GTX 780 is actually a work of art and does a stellar job of keeping that card cool, it simply can't hold a candle to a full-card waterblock that can absorb the heat from every heat-generating component on the card, especially the power circuitry. Suddenly you're not risking tripping the 780's boost clock thermal limits anymore, and the blower coolers aren't generating any more of a racket for your trouble.

Of course, building a custom loop is insanely daunting. This is the first time I've ever built one and while guides exist all over the internet, they all feel a bit incomplete in one aspect or another. There's also the fear of spraying coolant all over the inside of your case, or accidentally frying graphics cards when you install the waterblock, etc. It's also a decent amount of work, and it's not cheap. Truthfully, if I hadn't been able to put this together for AnandTech, I don't know that I'd have ever made the attempt. But the opportunity did present itself and now I can at least share the results with you.

The Components, Part 1
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  • dragosmp - Monday, September 30, 2013 - link

    Still, it is incomplete. The thermal transfer formula is simply Rth=rho*L/S, more thermal resistance (Rth) more the temperature delta is high between the source and ambient: deltaT=Power*Rth
    Asuming the power is constant, to decrease deltaT you need to decrease the thermal resistance, so:
    *S is the die surface, can't change that
    *L is the thickness of paste - you're right, it needs to be as thin as possible; put 2x too much and you have twice the deltaT
    *rho - thermal resistivity (1/lambda) - it depends on the material; Intel does use cheap paste with a conductivity around 3; were they to use fluxless solder or at least some AS5 they'd decrease the thermal resitance by a factor of 2 easily, thus offsetting a thicker than needed layer of paste.

    My 2 cents: for performance the paste must be removed and replaced with something better plus as you say remove the glue to reduce the thickness. Of course one should be careful not to chip the die, but these two things really help.
    Reply
  • Sadrak85 - Monday, September 30, 2013 - link

    And one more thing is the addition of onboard voltage regulation, which is a lossy process almost by definition. Meaning, even with the better TIM, I seriously have my doubts that the thermals could hit the level of IVB or SB. Unless Intel somehow has some magic way of using the voltage and amperage they're scrubbing off.

    *small note, a good motherboard input, in terms of electricity, would pass through the filters pretty cleanly, but because Intel sets the specifications for the input, I have my doubts that they require such a thing, since the feature they added to their chip was to save money for the motherboard vendor.
    Reply
  • leafonwind - Monday, September 30, 2013 - link

    The thermal interface material is minor compared to the interface distance. Thermal resistance is L/kA. Going from a millimeter of thermal paste to an 10 micron gap (typical of paste when applied correctly) will give a 50x improvement. The difference in k between a good thermal paste and a bad thermal paste is typically a 5x difference unless you get into exotic materials like cadmium. http://forums.anandtech.com/showthread.php?t=22618... Reply
  • gandergray - Tuesday, October 01, 2013 - link

    To bolster Von's point, see the work performed by Idontcare: http://forums.anandtech.com/showpost.php?p=3405318... . Reply
  • merikafyeah - Monday, September 30, 2013 - link

    Super tiny correction: While it is true that liquids draw away heat much better than air, one must be cautious not to mistake water as a good CONDUCTOR of heat, aka something that "transfers" heat very well. Water is in fact an INSULATOR of heat, aka something that "absorbs" heat very well. Reply
  • merikafyeah - Monday, September 30, 2013 - link

    Note wording on first page, third paragraph. Reply
  • ShieTar - Monday, September 30, 2013 - link

    Correct, but to be precise, neither air nor water will conduct heat quickly enough for PC cooling purposes, both are only used to absorb the heat before being transported away from the heat source.

    Which makes you wonder how a closed-loop, compressed air cooling system would fare against a water-cooling system. Heat capacity might still be lower for air than for water, even at increased pressures, but I assume that you can produce higher flow rates for a compressed gas than for a liquid. And you could use the required compressor in order to:
    1) Reduce the air temperature below room temperature before sending it to the heat sources.
    2) Increase radiator temperature over the CPU/GPU temperatures, thus achieving the same heat transfer with lower air flow rates through the radiator. Though temperatures above 100°C may be unsafe in a consumer device for several reasons.

    Does anybody know if such a system has been considered and tested anywhere?
    Reply
  • Death666Angel - Monday, September 30, 2013 - link

    Considered? Probably. Used? Not to my knowledge. If you have a compressor it makes more sense to cool the water used in the loop to just above freezing or even below freezing with the right additives. Of course, if you cool it that much, you have to worry about condensation, so most people I read about who use compressor cooling for their liquid (instead of large radiators) keep the water around room temperature and have the cooler in another room, to not be bothered by the noise.

    The stuff that is used to conduct heat away from the components inside the PC is the metal heatsink. In the case of pure air cooling you then push air through the metal heatsink fins. Because of the delta T you have the air warming up, the metal cooling and being able to absorb heat from the CPU/GPU etc. again. In case of water cooling, you have the water running through the heatsink (usually some very fine canals inside that increase surface and flow rate) which absorbs the heat from the heatsink and gets transported to (large) radiators where air is again pushed/pulled through the radiator fins in order to cool it.
    Reply
  • Sadrak85 - Monday, September 30, 2013 - link

    Used all the time; Nitrogen is the most common component of air; it is compressed so much as to become a liquid. Then, thanks to the Carnot cycle, cooling the liquid to room temperature results in it boiling and becoming ultra-cold air, which cools a processor.

    A similar thing happens with your refrigerator.

    These coolers, however, require massive power to get them to that level, so they're only really useful for very niche-applications, but the equipment isn't really that hard to find. An evaporator will cost you something like $200 to $300, and then the Nitrogen.

    Now, if you're talking about keeping the air gaseous, then what you'll find is it just isn't possible. Cooling it very much with pressure on it will result in it condensing to liquid. If you just compress it, without the cooling, you'll heat it up, of course, which is how your diesel engine works.
    Reply
  • ShieTar - Monday, September 30, 2013 - link

    Fair enough. I am fully aware of the cooling concept via liquid nitrogen boiling itself, but I was considering a much simpler concept. Maybe I should describe it in a bit more detail.

    Imagine a closed air (or just nitrogen) system where the air pressure is about 3 bar within a radiator and about 2 bar when it circulates within the cooling blocks. You can have temperatures around 200K at 2 bar without liquifying, and not that much higher at 3 bar.

    So you offer your GPU/CPU coolers 2bars of air at 200K, maybe heat it to 220K, compress it to 3bar/330K, cool it back down to 300K (close to room temperature), decompress back to 2bar/200K.

    What needs a little more math is, just how much volume of gas do I need for this to transport 600W or so of power by this concept. And how much additional energy do I waste on the compression process. And probably, just how horribly noisy will this setup get with 2bars of air at high velocities getting pressed through the cooling blocks at high velocities.

    Yeah, the more I think about it, the worse the whole concept sounds. Nevermind it.
    Reply

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