Watercooling F.A.Q

So, you want to do some watercooling, right? There are plenty of reasons to; for starters, water transfers heat much, much better than air does. Custom loops have the potential to look amazing, as well, easily making your rig have that "million dollar feel." However, it is just as easy to make a mistake, have worse performance than air cooling, and ruin your hardware. That is what the internet is for.

For starters, you need to know some basic parts that are used for watercooling.



Arguably the most well-known part of WC is the waterblock, because, after all, it is what the water flows through to cool the components. There are thousands, and thousands of different blocks out there, for RAM, mainboards, CPUs, GPUs, even HDDs and PSUs. Each block is different in what it fits with, especially on GPUs, which require a specific design to fit the PCB. On CPUs, most blocks are multi-socket compatible, and will fit on a wide-range of AMD and Intel sockets.

When choosing blocks, you want whatever provides the highest performance with the least restriction, but in all practical applications with modern CPU blocks, it is best to pick what looks the best for your budget. There are clear victors in performance, but in my honest opinion, what fits your aesthetic preference works.

My go-to blocks for CPUs are, in no particular order:

  • Heatkiller CU 3.0 (older, but amazing build quality and looks)
  • Koolance 380i (one of the best performing Intel blocks on the market)
  • Koolance 370i (cheaper alternative to the 380i, and possibly better looking)
  • XSPC Raystorm (cheap, and great performance)
  • Swiftech Apogee HD (another hard hitter in performance)
  • and the EK Supremacy Plexi (looks great, if you're into the CSQ design, and performs well)

Most companies offer AMD mounting brackets, either included, by request, or for individual purchase.

For GPUs, you can't really recommend blocks as a general rule, because each card requires a different block, for FC blocks. There are universal GPU blocks, but I, personally, find them to be too ugly for my personal taste. If you can't find any GPU blocks for your model of GPU, it is the only option, but only non-reference cards would have a risk of not having a block. Instead of recommending a model of GPU block, though, I am going to recommend just matching companies for aesthetic reasons. Koolance 380i CPU block? Get a Koolance GPU block to match. EK Supremacy Clean CSQ CPU block? Get an EK Clean CSQ GPU block. The performance of modern FC GPU blocks are so close, it is an aesthetic decision.

Cooling RAM and motherboards is completely pointless unless you are doing it for aesthetics. Cooling PSUs and HDDs is ridiculous, and shouldn't even be thought of. If you really want to cool your RAM and/or motherboard, go ahead, but you're pretty much wasting your money.



If you don't already know, a pump moves water. You need a pump to push water through all of your blocks and rads to actually do some cooling. There are two big choices for high-flow pumps; the Laing DDC, and the Laing D5 Vario. They are both fantastic pumps, and are relatively close in performance, but the D5 is king. I personally prefer the DDC for the lower-profile, flat top, but that is just me. In any case, both pumps are overkill for 90% of loops. You can coo a few GPUs, a CPU, and over 1000mm of radiator space with a single D5, but people with half that will use two or more; wasting your money. If you are pressed for cash, look around on FrozenCPU, PerformancePCs, and such, and pick any cheap 12V pump, but be warned, it may not perform nearly as well as the impeller-based DDCs and D5s, and will probably not be long for this world.

If you do have the budget, and want to run dual pumps, there are some good reasons to do so. Not only can you crank each pump down for less noise, but you have redundancy; if one pump fails, you have at least one other to keep your components cool. There are some reservoirs that allow you to mount two DDCs or two D5s together, and after-market pump tops that let you mount two or more pumps together, as well. Either way, if you want multiple pumps, I'm not stopping you. It can help, but most likely, you're wasting money.



Radiators, if you didn't know, are a collection of thermal mass that you pass water through to cool the water, which is cooling other things. Radiators are all about surface area and restriction for flow of air, and air flow. A denser radiator, than has more fins per inch (fins like a standard heatsink has), requires lower RPM fans, with higher static pressure, and fans with lower FPI (fins per inch), require more CFM, with less static pressure; simple to understand. As a general rule, thicker radiators perform better, but require higher SP fans to drive, and the inverse for thin rads.

In terms of how much radiator space you need for your system, the standard assumption seems to be 120mm * (number of components being cooled), plus an extra 120mm for extra cooling, overclocking, and general safety. 120mm radiators are not the only ones out there, though. There are 80mm rads, 140mm rads, 180mm rads, and variations within those, such as triple 180mm rads, quad 140mm rads, and such. The larger fan size means more radiator space, and can mean lower RPM required on the fans for equivalent cooling, yet lower noise. However, the selection of fans above 120mm and below 120mm is much smaller, and the quality of those much less abundant. I am a huge fan of 120mm rads, but would like to see more 140mm fans out in the market, to make the 140mm radiator market more common.

Now, I don't like to recommend brands, but almost every single radiator I have ever seen come from Alphacool has been amazing in terms of build quality, and performance, especially the Monsta rads (a 560mm Monsta will cool just about anything). However, many, many other companies have great products, including:

  • XSPC RX , AX, and EX rads (RX are thick, AX are thick, EX are thin)
  • HW Labs Black Ice Stealth, Xtreme, Alpha, and SR-1
  • EK Coolstream rads, coming in a variety of thin and thick
  • Swiftech "Extreme" rads (very nice build quality and price)
  • and the aforementioned Alphacool rads, including the UT30, UT45, UT60, and Monsta series 

Now, that list is by no means extensive, but those are rads that I am comfortable with, have seen, used, and would recommend to anyone.



Reservoirs are, in watercooling, exactly what they are everywhere else; a vessel for water or other coolant. They are not necessary, but make bleeding and filling a loop much easier. Getting a huge reservoir, to me, looks unsightly, but in some cases (literal cases, the house for your computer), can look good. Get whatever fits your preference for looks. I prefer smaller to medium-sized tube reservoirs, but some people like bay reservoirs, others like micro-reservoirs, or, like I said, none.

You can use more than one reservoir in a rig, but aside from aesthetics, doesn't help or change anything.

It's pretty hard to have a bad res, but I can highly recommend the line of reservoirs that Bitspower; Bitspower Multi Z. Great looks, build quality, and decent price. Just get what looks good, what you like.


Tubing and Fittings

Tubing is what lets the liquid, or coolant, travel from one place to another. Fittings are used to secure each end of the tubing, add fill ports, drain ports, improve aesthetics, and make your job easier.

When choosing standard soft tubing, you need to look at a few things; what size ID you want, what size OD you want, what color you want, and what kind of coolant you will be using. Some tubing is really small, other tubing is really large, and certain sizes of tubing are so large that the fittings can't actually fit on the waterblocks, next to each other. In most cases, though, you won't see that problem.

I personally think huge tubing is ugly, and pointless; a good size is 3/8" by 5/8"; it isn't huge, but has a lot of flow, and a wide selection of fittings. 3/7" by 1/2" has a smaller wall, and may be better for harder curves, but 3/8" by 5/8" is a great size.

Certain tubing has plasticizers, which will cloud the tubing, and others have anti-microbial coatings, and such, which can also interfere with your loop. I recommend Primochill Advanced LRT for soft tubing, because you don't have te deal with any of the issues that other tubing provides with plasticizer, and such, but plenty of people like Tygon, or even Masterkleer.

Soft tubing is not the only kind, though. The two other well-known and implemented are hard acrylic, and hard copper pipe. Some people use nickel-plated copper, which, I personally think, looks absolutely amazing, but others go with a raw copper, or clear acrylic. I have seen a few people use frosted acrylic, which is drop-dead gorgeous, but hard to pull off. All a matter of how much work you want to put in, and how much money you have (copper tubing is expensive to use.)

Fittings come in several types. for different types of tubing, and different types of attachment. Soft tubing uses two main types; barbs, and compression fittings. Barbs are literally just an elongated piece of tubing or pipe with wings that  you push the tubing over, and usually clamp the tubing to, with a zip-tie, or other fastener.However, comperssion fittings still have the elongated piece of tube/pipe, but also have a compression top, with at least one o-ring, that screws on to the bottom part of the fittings, compressing the tubing for a tight-seal. Compression fittngs are more expensive, but well worth it, in my opinion. You also, with compression fittings, get the variety of 45 degree, 90 degree, even 180 degree fittings, plenty of different finishes, and thousands of products to choose from. Bitspower is arguably the best company for compression fittings, but XSPC, Koolance, and even EK have plenty of great options.

For hard tubing, that is, acrylic or copper, you will most commonly see push fittings, which are like a barb, but inverted, where you push the tubing inside of the fitting, rather than the outside. Usually, there is at least one o-ring inside the push fittings, but in some cases, there are several o-rings, or even teeth that add for a more complete seal. I am a fan of the toothed ones, but the selection, compared to compression fittings on soft tubing, is much more limited. Festo is my go-to brand for push fittings, but AquaTuning also has a great selection. Bitspower, though, does have a pretty wide selection of compression fittings for acrylic tubing, which are not only expensive, but really well made, as with most, if not all Bitspower products. Koolance offers some compression fittings meant more for copper tubing, although, they also work with acrylic. I highly recommend compression fittings, both for hard and soft tubing, if the budget allows, but if not, barbs, or, for hard tubing, push fittings, will work just fine.



Many people want to use these extravagent, thick, and colored coolants, but in reality, the best coolant is distilled, di water, with, maybe, PT Nuke, or a silver coil, for anti-microbial and anti-corrosive impacts. If you want color, try colored tubing; it will always be the right color, and you can use distilled water, which is not only the cleanest for your blocks, and easiest for your pump, but performs the best thermally. Some people say that pure water can cause rust on your blocks, but if you are using distilled, di water, you will not have any issue with that. You are much safer with killcoil, or other alternatives to it, but in all reality, microbial contamination is a more prevalent issue that rust. Galvanic corrosion, however, is also a big concern, but that is caused by mixing metals, usually, the combination of copper with aluminum. Throw copper in with iron, brass; you'll be fine. Aluminum? Corrosion within the week.

Coolant can stain tubing, and gunk up blocks/rads/pumps, which is why I don't recommend it, but if you are going to use coolant, stick with a really fine solution, try to keep it as thin as possible. Some really popular ones inculed Ice Dragon nanafluid and Mayhems Pastel. Mayhems Pastel is pretty thick, compared to water, but is one of the highest quality coolants out there. Looks great, I think; I will probably be using some Pastel Lime Green in my loop, soon (I know, I know), but, in the long term, can lead to discoloration of your tubing, or staining, as with any coolant. It depends on the tubing, too; Advanced LRT is really good about not staining, and remaining cloud-free, but you are always going to be safe from discoloration with di water.



Loop Order

It is often thought that loop order plays a huge role on performance of cooling. This can be true in certain situations, but in all practical applications, as long as, physically, the reservoir feeds the pump directly, which requires a physical placement of the res above the pump, and directly before it in loop order, the rest of the order can be whatever you want.

When dealing with multiple blocks, however, you have the option for serial or parallel, and this is a hard thing to visualize for people, sometimes.

In series, each block, radiator, and pump are hit individually, as well as anything else in the loop, obviously. You go from one to another, gathering and dispersing heat as it goes. It is the most logical way, if you think about it. Just like in electricity, in series, everything is hit, in order, a complete circuit, a complete loop.

Parallel, however, offers more than one path for the water to flow, so that you, theoretically, have less flow, and, ideally, less resistance, but most of all, you are attempting to add to the cooling potential through the combination of the two. In terms of performance in the real world, the temperature difference between the two, though, parallel is actually a bit warmer, at the extreme ned, 2 to 3C hotter, which I believe is because, despite common belief, I think it adds more resistance, because, while the water is now able to take the path of least resistance, you are still colliding the water with itself, which, in the confines of the blocks, usually GPU blocks, would add to the resistance. Still, I am a fan of the look of parallel, compared to serial, but the time it takes to bleed seems to be substantially higher with parallel blocks, once again, especially GPUs and radiators.

If I have confused you, here are some diagrams and pictures for reference:

Parallel GPUs -

In use:


Compared to serial -

In use:


Other than dealing with serial and parallel, the most important part of loop order is whatever uses the least tubing, and looks the best, to you.


Filling and Bleeding

Now, I have used the word bleeding a lot, in the text above. It simply means to remove the air bubbles from your loop, which can cause issues with performance, flow, at severe ends, damage your pump, bust mostly, look bad.

Because there are so many methods and styles of bleeding, I will stick to the easiest method, which I still hold to be the T-line, also known as a t-block, combined with your res. They can be both terribly ugly, and gorgeous, it just depends on how they are implemented. Bitspower makes a really nice, compact t-block, which I much perfer to the older, large, ugly blocks, but that it just personal preference, really; they all do the same job.

A T-line is literally a fitting that splits like a T, but upside down, which can be used for bleeding, filling, and an outlet for evaporation, which isn't much of an issue, but that is another discussion altogether. Bleeding on a T-line is really limited, though, so many people use their reservoir with it for the fastest possible, most effective way to bleed and fill the loop. How do you bleed? You let your loop run. If you have an outlet, such as the T-line, or some other custom concoction, then you will have to run for several hours for the coolant to push all of the air out, but if you use a res, or a res and T-line, then an hour at the longest, I would say, is enough for the loop to bleed. The pump, not having to push air anymore, will, if you have a particularly noisy pump, make less noise with a properly bled loop, and be happier with what it is pushing (they're meant for water, not air). Running air through your pump, or running dry, is bad for the pump, and is advised that you do not, at all costs, do it, if you can avoid it. This is why the reservoir, or other fill port, is always located directly above the pump, both in loop order and physically, so it always has a stream of coolant.

When filling the loop, my recommendation is to use a syringe, as opposed to a funnel, or just a cup. You have more control over the filling, you are more precise, which reduces splashing, and keeps everything nice and steady. Simply pour into your fill port, or, in most cases, the top of your reservoir, steadily, and as quickly as your pump needs it. Continue filling the loop until you have coolant filling the tubing completely, and as much of the reservoir as you want (remember, leaving too much room, with high enough flow, can cause a dripping or splashing sound, if your loop fills the res from the top, which it may, or may not). The most important part, though, is to have the tubing completely filled, as well as any blocks you have, with coolant, be it a mix, or plain water.


Will update later with more pictures, sections on vendors, flow analysis, and more :)

Nice Thread brennan.

When mentioning GPU blocks, go here: http://www.coolingconfigurator.com/ as it will tell you if your GPU is reference base and tell you suitable EK blocks. (as it is run by EK)

Amazing guide but you should probably put some info in about coolants. Like which ones to choose from and using coloured coolants with clear tubing can cause the tubing to change colour.

It's a WIP, but I added the coolant section, or most of it.

This is a great FAQ, man. 

I use a liquid based food coloring to color my Distilled water. It WILL stain clear tubing, but it has no suspended particles, so nothing will get clogged. 

Added parallel, series, filling, and bleeding.

As the Customer Support and RMA rep for Swiftech, please let me know if any of you have any questions regarding our products, or just general liquid cooling questions.

How the F&@k do your fittings work? I bought Bitspower, and they work great. I have Koolance Barbs, and they work, but the Swiftech do not work. I bought them because I believed the whole "finger-tight is not enough" business, but I cannot even get them to the threads. I have the 3/8 ID 5/8 ODwith matching PrimoChill LRT. 

I cannot even thread these! What am I doing. wrong? I heated the tube with hot water to get the barb all the way in. The barbs are in fine just like the Bitspower. How do get the outer part on? I cannot figure it out. 

http://www.flickr.com/photos/[email protected]/9795836994/

One thing I read when I built my loop is that sometimes it's a good thing the fitting doesn't fit all they way.. but in your case there's quite a gap..


Hi again Garry, please read my most recent email to you regarding this. We'll get you taken care of.

Brennan what are your thoughts on changing/cleaning the loop out? I've been running mine about a month now, rarely any hard gaming lately and I'm wondering what I'm going to do when that time comes. How gunky/algae have you ever let your components become? I saw pictures where it looks like they peel their heatsinks right out of the lake.

Another concern I have is sunlight. I have my computer glass facing towards a window but I have relatively good enough blinds, at least no direct sunlight. It only gets rays early in the morning with sunlight through that window but like I said it's covered, and I still worry about it.

As long as you have a killcoil or deadwater, you shouldn't have any growth of any kind, sunlight or not.

If you suspect you're growing something, I would recommend immediately disassembling it, flushing everything vigorously with vinegar, running the loop with it for a couple of hours, (Out of your system) and purchasing one of the former options..

Growth is never okay.

Just want to say a quick thank you for taking the time to type this out. Much appreciated. 

what an awesome read. Thanks dude

How can you tell if the coolant is reaching the pump if you have solid tubing? And would I have to do anything special if I did go with the mayhem pastel. I have black tubing and going with a black liquid I just have a few places like the res which will be clear. 

If the pump is directly below the reservoir, both physically, and in loop order, then the coolant, according to physics, should be reaching it. Also, if coolant is coming out of the outlet of the pump, it's a safe bet that coolant is pumping into it.

Awesome thanks I have been just worried a bit about water cooling and my OCD wont let me do anything until I figure everything out 100% :p

Alright, so I  have this card http://www.newegg.com/Product/Product.aspx?Item=N82E16814202025

this CPU http://www.newegg.com/Product/Product.aspx?Item=N82E16819116502

I'm thinking a 240 mm radiator, possibly overkill on the pump, and this gpu block I think should work. http://www.swiftech.com/mcw82vgawaterblock.aspx#tab2

Looking for pure performance, noise is not an issue, and it can be as ugly as it wants so long as it works.

What does everyone else use on their hardware when watercooling? Brennan has a nice list, any good U.S. sellers people like to go through?