The Neophyte's Custom Liquid Cooling Guide: How To, Why To, What To Expect
by Dustin Sklavos on September 30, 2013 12:01 AM ESTIf our whole hypothesis is that watercooling is (in most cases) superior to air cooling, then we need some measure of data to prove it. That means building our system and cooling it under air first, and seeing just how much overclocking performance we can get out of it before heat becomes too serious an issue. This is difficult to fully quantify; luck of the draw means we could wind up with stellar, efficient overclockers on both the CPU and GPU sides, or absolutely lousy ones. Haswell, in particular, seems to be afflicted with unusually high variation between individual chips.
To get some idea of how assembly goes in the Corsair Carbide Air 540, you can refer to my review. Suffice to say the system came together pretty easily. The modular nature of the SSD cages allowed me to remove all but one, and the 3.5" drive sleds went unpopulated but connected for the future. My biggest concern was the lack of clearance between the Noctua NH-U14S and the top GeForce GTX 780.
It looks like they're touching, but fear not, they're just playing the scariest game of "I'm not touching you" I've ever seen. This board is designed for quad-GPU graphics systems, which puts the primary PCIe x16 slot at the top. The upshot of that is the excellent spacing between the two cards: they're two slots apart, allowing for plenty of airflow between them.
Ignoring for a moment the fact that I've always been lousy at cabling, we're presented with something of an issue. The Carbide Air 540 doesn't really necessitate neat cabling since that cubby in the bottom left of the photo is typically where the mass of cables always goes. However, the AX1200i is a very deep power supply, and that cubby is where I intend to put the pump and reservoir. This is, in my opinion, a failing of the Carbide Air 540's design: there's a tremendous amount of open space at the top right, and no real way to occupy it.
Overclocking on air wasn't actually tremendously difficult, but it's where I ran into some real issues with the i7-4770K. This is...not a spectacular sample. VRIN starts at 1.812V, and the VCore's default voltage is already at 1.2V. With load line calibration set to Turbo, I was able to get the chip stable at 4.3GHz, but VCore was reading ~1.3V in Windows. Thermals were reaching the low 90s under OCCT. 4.4GHz and 4.5GHz were both bootable, but thermally too dangerous. For stability testing, I did a five minute run of OCCT followed by a run of POVray 3.7 RC, per Ian's suggestion.
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The two GeForce GTX 780s fared a bit better. I maxed out the power and temperature targets, and while the fans got pretty loud, I was able to get a +125 offset on the core and stunning +550 offset on the GDDR5, leading to a peak boost clock of ~1150MHz and a GDDR5 clock of 7.1GHz. Any higher than that on the GDDR5 would work, but produce artifacts. Peak boost was pretty tough to maintain, though, with the cards regularly dipping back at least a couple of boost bins under EVGA OC Scanner X. Stability testing was initially done with OC Scanner X, but I found it to be remarkably unreliable. Per Ryan Smith's suggestion, I switched to using a Crysis Warhead benchmark and then running Fire Strike Extreme in 3DMark. Crysis Warhead was pretty good at ferreting out unstable overclocks, but 3DMark was fantastic at it.
All in all, the overclocks were decent, although the i7-4770K apparently lived to underwhelm. I'm also a little disappointed the 780s couldn't hit 1.2GHz under boost on the core, but the excellent GDDR5 overclock takes some of the sting off of that.
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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.
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...gandergray - Tuesday, October 1, 2013 - link
To bolster Von's point, see the work performed by Idontcare: http://forums.anandtech.com/showpost.php?p=3405318... .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.merikafyeah - Monday, September 30, 2013 - link
Note wording on first page, third paragraph.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?
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.
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.
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.
UltraWide - Monday, September 30, 2013 - link
Excellent article, I enjoyed reading this journey into water cooling. Keep up the great work!