Your Guide to PC Liquid Cooling

Your Guide to PC Liquid Cooling

From Hobby to Obsession

What’s the difference between a guy with a hobby and an enthusiast? The way I see it, an enthusiast is always okay to sacrifice more time and money for something they’re truly passionate about. If you find it hard to explain to your friends and family why you’ve bought your tenth guitar amp when the previous nine were not enough – forget it, you’re an enthusiast, and only those of your kind will genuinely understand your way.

Well, I have a confession to make – I am a PC enthusiast. This journey started from the video games I’ve been sincerely loving since I was a kid. I was both enjoying big single-player titles and thriving in competitive multiplayer games, even participating in local championships in my town. Anything that would run on my budget aging PC my parents bought me in high school would do.

As time went on, I started making small amounts of money myself (summertime jobs mostly), saving a part of it for my hobby. I remember very vividly that feeling of joy and happiness when I held my first gaming mouse, a Logitech MX518, which replaced my previous $10 device, probably from Genius. At that very moment, I felt like a professional esports player, no less. As I grew older, my income increased, and I was able to throw more money into this: large mouse mats that cover half of the desk, mechanical keyboards, monitors with increased refresh rates, expensive headphones with high-quality standalone mics, top-tier graphics cards… And strangely enough, as I was spending more and more money, I started playing less at the same time. Technically, I was still in front of a monitor most of my time, but now watching YouTube hardware reviews more often than actually playing. Hardware and PCs themselves became my new passion, which doesn’t make sense to many people around. Who would want to spend so much on something you do not even put to good use? Well, an enthusiast. [1]

Liquid Cooling: Not for the Faint of Heart

Now, wait a minute, isn’t this article about water cooling, why am I reading your life story? Don’t worry, we’ll get down to this right away, but before we start, I feel the urge to post this: liquid cooling is entirely an enthusiast thing. It isn’t to say that no one else is allowed to do that, but if you are not ready to spend time, spend money, get disappointed and spend even more – stick to traditional air cooling or pay someone who will build a loop for you: there are many talented PC modders who do amazing client builds.

I want not to discourage you with these words, but to save you from a potential setback. And if you still ask yourself whether or not you want it, and the answer is still “Hell, yes!” – welcome to the club. 🙂

Do I Need Water Cooling?

If you put it that way, then no, I doubt anyone needs it at all. One could barely imagine a real-life scenario in which you could say that liquid cooling is an absolute must. Sure, you can significantly decrease your hardware temperatures, but that does not mean you cannot be all right with air cooling. A brand-new Tesla X can be fantastic, but that does not imply you cannot keep driving your 2010’s Ford that is still in great shape. [2]

The best go-to scenario for water cooling is probably having a top-tier graphics card (or several of them). For instance, NVIDIA’s TitanX and 1080Ti cards are ultimate powerhouses with an ultimate TDP (thermal design power) of 250 Watts. The amount of heat released by those 250 Watts of energy is gargantuan, and you need to dissipate it somehow. Otherwise, as a card reaches its maximum allowed temperature, it attempts to cool itself by automatically decreasing its operating frequency. This process is called “thermal throttling,” and it is entirely normal. [3]

In practice, that only means a card starts operating at its normal clocks, giving up those extra frequencies provided by the Boost technology. Yes, heat is one of two most notorious hardware killers (the second one is over-voltage), and if you find a right way to dissipate those 250 Watts of heat, you prolong an expensive graphics card’s lifespan. However, with relieving components from an overheating threat, you instantly introduce them to another one — leaks. Compared to heat that causes slow degradation over a long time, a liquid is an instant hardware killer that is far more dangerous. So nope, even with top-tier components that are HOT, water cooling is not a miraculous solution. [4]

How Much Does It Cost?

I would like to pair this question with “How much time will it take to build one?” and give one answer to both of them: “Only God knows”. Let me demonstrate the way the cookie crumbles with another story.

My first water cooling experience started with plans to assemble a custom loop in an NZXT S340 Elite case — a cozy and beautiful chassis many people love. I did a fair amount of investigation (or better, I thought I did) and concluded that I would manage to install three radiators (1×240 in front + 2×120 at the top and rear). Which I was unable to do even after drilling two holes for pass-through ports at the top of the case (I seriously considered mounting a radiator outside the case after numerous attempts to fit it inside), and which ultimately led to buying an entirely new case that was relatively larger.

A new chassis — a new pump\res combo! I didn’t need to go with the smallest combo available anymore, so I ordered a bigger tube. Which did not fit, yay! I mean technically it did, but not in the way I wanted it. Long story short, the 240-mm radiator was the only piece of hardware that survived long enough to see the final build. Other parts went into the closet or were sold to some random folks around the Internet (used liquid cooling parts are not exactly the easiest thing to sell, so be prepared to make huge discounts for people willing to buy them). In the end, I spent somewhere around € 1000 and five months to build a pretty simple loop with 1 CPU and 1 GPU. [5]

Not only does the final build cost depend on how accurate your initial plan was, it also hugely depends on what parts you use. Same rule as with everything else in this world applies to water cooling — parts from well-known manufacturers (EK Waterblocks, Bitspower, Phanteks, Singularity Computers, etc.) cost more. If you are on a budget that you do not want to stretch a lot (although you are almost certainly doomed to do that once you start building) — you can save quite a few pennies by purchasing stuff from other vendors. [6]

For instance, Barrow: a Chinese manufacturer that features a wide range of water cooling parts with very decent quality. There is a video on JayzTwoCents YouTube channel (be sure to check out this guy, he has tons of useful content regarding water cooling) where he compares the EKWB’s Supremacy EVO block with the cheapest, the ugliest, almost DIY-looking waterblock from Amazon that is five times cheaper. And they performed virtually identically! Makes one wonder whether it’s worth paying more at all.

The tricky part here is to know what components are okay to purchase from AliExpress for nothing, and which are more quality-dependent. We’ll get to this later when we start talking about each loop node separately.

All-in-One or Custom Loop?

AIO (all-in-one) solutions are aftermarket coolers with factory-assembled “closed” loops. Some of them allow moderate maintenance like re-filling the coolant that may evaporate over time, but in a nutshell, you just take them out of the box and install them. There are much more CPU AIOs than similar solutions for graphics cards because motherboards have unified CPU sockets, unlike GPU vendors that may go for any “non-reference” board design.

At the same time, water-cooling a CPU makes much less sense than water-cooling a GPU since processors emit much less heat and a good old “tower” air cooler will do just fine (often, even better than a mediocre AIO). Apart from that, AIO issues are: On the bright side, AIOs are much cheaper and, sometimes, sexier. I’ve been using the NZXT Kraken x52 for a couple of months and boy was it beautiful! Another good use-case for buying an AIO is building inside tiny mini-ITX cases that cannot accommodate large (read that as “effective”) air coolers. [7]

To sum up, if all you need is a CPU cooling solution that is compact and easy to work with — AIOs are worth buying. Other than that, if you have a roomy case (especially manufactured with having a custom loop in mind), I would not recommend that. AIOs aim to be jacks of all trades, but realistically are masters of none.

Anatomy of a Custom Loop

A water cooling loop follows the same principle an air cooler does: it takes heat from a hardware (e.g., a CPU die) and dissipates it into the air. Any loop consists of the following nodes:

  • Pump
  • Reservoir
  • Radiator
  • Water blocks
  • Tubing
  • Fittings

And a couple of auxiliary nodes that you may or may not have:

  • Flow meter
  • Temperature sensor
  • Drain port

Now that looks complex, doesn’t it? Don’t worry; we shall break it all down below. [8]

Pumps

Back in the days, the entire liquid cooling department had significantly less attention from the public. It was a thing for a very small circle of people. There were much less ready-to-use parts you could buy, not to mention they would cost you a lot more than today, so people often went for some wicked DIY solutions for their loops. I’ve seen quite a few mentions of regular fish tank pumps employed for cooling PC hardware. Since those days water cooling has grown dramatically and you can finally leave your fish alone.

A pump is an electrical motor that rotates an impeller, which creates pressure that moves the liquid. The pump case connects with a top that has an inlet and outlet ports. The liquid that flows inside a pump cools this pump down and, most importantly, lubricates it (something called “a wet rotor design”). For this reason, never run your pump dry; doing so may kill the pump in a matter of seconds.

In a couple of years, the initially large variety of available pumps has narrowed down to two renowned models from the same manufacturer: Laing D5 and Laing DDC. You may also meet the “Xylem” name instead of “Laing” but don’t be confused, those are different brand names for the same vendor.

The D5 pump is larger, runs cooler and quieter, delivers a maximum flow rate of ~1500 liters per hour and provides a maximum head pressure of ~4 meters (a head pressure demonstrates how high a pump can push the liquid if the outlet port aims 90 degrees upwards). The DDC pump, in turn, runs much hotter, has a bit lower flow rate (approx. 1000 liters per hour), but delivers a much higher head pressure (up to 7 meters). It also occupies significantly less space, which makes it a better choice for cozy cases. Also, the higher head pressure means DDC pumps are better to use when you have multiple water blocks and a lot of turns in your loop since those elements increase the flow resistance and make the liquid lose part of its initial pressure.

Reservoirs

As mentioned before, a pump has a top housing (or “pump top”) which provides inlet and outlet ports. That’s where 3rd-party vendors come into play. See, you can buy a DDC or D5 pump from almost any liquid cooler seller: Alphacool, Swiftech, EKWB, etc. And all of them will have the same Laing (Xylem) pump at their core. The difference between these models is the pump top they use. Vendors claim that their after-market tops deliver increased performance compared to the factory top (e.g., EKWB states that their EK-XTOP DDC 3.2 PWM Elite pump increases the hydraulic performance up to 15%). If you wish, you can purchase a pump and a pump top separately, then assemble them manually, but this hardly makes any profit compared to buying a single pump+top unit. For simplicity, I will refer to a pump+top combo simply as “pump” from now on.

If pump tops are not a big concern since you will most likely have them pre-installed, reservoirs have a bit more about them. First of all, again, you may have a pump and res as two separate units, or as a single combo unit. Much as with pump tops, the choice is entirely yours as it has no impact whatsoever on the overall loop performance. Pump\res combos are more comfortable to install but require more vertical space. Separate units are better for more sophisticated loop designs where you can hide the pump in the case basement (under PSU shroud).

Regardless of your choice, remember that you must not run the pump dry, so you need to have a reservoir directly feeding your pump. Place a res must somewhere above the pump with its outlet connected to the pump’s inlet, and let the gravity do the trick.

Tip: Pumps have pre-defined inlet\outlet ports whereas reservoirs do not — if a res has multiple ports you can utilize any two of them. Just do not forget to plug the rest of them.

Radiators

There is also a rectangular pump\res combo format that fits 5’25-inch case bays, which typically hold DVD\BluRay Drives. Following a modern trend, major case manufacturers keep ditching those 5’25” bays to favor an unrestricted airflow and a sleek appearance, so these pump\res combo units become less and less popular. But yes, these are still viable if you want them.

Many blogs and videos focus on differences between D5 and DDC versions, technical specs and so on, but say nothing about this, at first sight, simple aspect of a build. First, find a user’s guide that came with your case or Google for it. Find a section that should be called something like “water cooling compatibility” and check for pre-drilled holes your chassis has. For instance, my Phanteks Enthoo Evolv has a bunch of mounting holes in a motherboard tray and the bottom panel. Inspect all mounting spots suggested by a manufacturer and search for other people’s build around the internet — this should give you a clue what units can fit in your case.

You may need to drill holes manually and\or use tools like Dremel to cut through case parts that are in the way. There’s also a more straightforward solution that can save you from potentially ruining your case: pump brackets. Typically, you have a radiator on the case front or bottom side, fans facing outside to intake air and push it through the rad. Fan mounting holes on a radiator’s opposite side remain free. Brackets attach to these spare holes so that your pump \res combo is mounted directly to the radiator.

Radiators are the only loop parts responsible for disposing of the heat while remaining nodes merely transfer it, so it is quite relevant to pay attention to what you’re buying. Forget everything you heard before: size DOES matter. The bigger your radiator is — the more surface area it provides — the better it dissipates the heat.

Radiator lengths are measured in the number of fans you can stick to one side. So you have “single,” “dual,” “triple” and “quad” rads to chose from (there are rads for five fans, but it’s pretty hard to find a case that can accommodate these monsters). Two most common fan sizes are 120x120mm and 140x140mm so you can calculate the radiator length. For instance, a duo rad designed for 140mm fans will be marked as a “280mm” rad. In return, if you see a “360mm radiator” in store, you should be able to read it as a “triple rad for 120mm fans”.

The second radiator size dimension we are interested in is thickness. Unlike length that is unified to fit fans, the rad thickness is entirely up to a manufacturer. Typically, you have sub-30mm “slim”, 30–35-ish “medium” and 40+ “thick” rads. You can find 80+ mm rads, but again, that is if you have a giant ultra-large case that has enough room for these bad boys.

A ubiquitous question is which size dimension has more impact on the loop performance, i.e., whether a slim but long radiator will outperform a thick but short one or vice versa. Remember this: increased radiator length gives your loop a much, much more significant boost than an increased thickness. Always go for length first, then thickness because the latter does not usually have that much of a difference. To a certain extent, however. [3]

Take some time to study this xtremerigs.net radiator review. Pay attention to 360mm radiators from EK Waterblocks: the difference between a medium and a thick models is negligible, just 5.7 Watts\10deltaT. But switching to the slim SE line gives you a massive performance drop of 25.9 Watts\10deltaT, which places SE radiators among the worst. So my advice would be going for medium-thick rads while getting as much length as your case allows you to.

Speaking of cases, most manufacturers do list supported radiator sizes in case specs. Unfortunately, this applies to radiator lengths only, which makes sense because the thickness is limited by your specific hardware (for example, you may be unable to install thick rads on top because of your motherboard’s tall heatsinks, or in front because of a long graphics card). Another problem with case specs is a lack of information about the possibility to utilize two radiator spots simultaneously. For example, the Phanteks Enthoo Evolv case supports 360-mm rads in front and on top, but is it possible to mount two medium

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