watercool MO-RA3 radiators

There are a few basic components that we must have as water coolers. Water blocks for our parts, pumps to move our coolant, and radiators to move the heat to the outside air are the most fundamental parts of a PC water cooling system.

Blocks and pumps are compact by design and there are options that will fit just about any setup.

The basic nature of a radiator makes designing it to be more compact problematic – its function is tied intrinsically to its size.




With SFF systems and cases getting to be more and more popular, and people stuffing hotter and hotter components inside, the logical evolution of the standard PC radiator is to move it outside the limitations of the case.

External radiators aren’t new, but like side panel windows and case lighting in years past, their popularity is driving change in the industry.

Some of today’s external radiators are beautiful pieces of fabrication made to be seen and designed to be as eye-catching as the PC itself.

One of the best-looking and most effective examples on the market today is the MO-RA3 from Watercool.



An abbreviation of Monster Radiator, the MO-RA3 is available in several different versions, differing in size, color and fan mounting options.

All of these external radiators have a few things in common.

- Available in black or white powder-coated steel or polished stainless steel

- Round copper tubes and aluminum fins

- Optimized for low-speed fans with only 9 fins per inch

- Six G1/4 ports


Those are all great common features for low-restriction radiators optimized for low-speed fans.

There are a few differences between the available models.


The MO-RA3 comes in two sizes: 360 and 420. Don’t take these sizes the same way you would a more standard radiator though.

To calculate the amount of fan surface that a MO-RA3 has, you need to take those size numbers and triple them.

In other words, a MO-RA3 360 offers a massive 1080mm of fan-mounting surface, and the 420 model has an even more impressive 1260mm.

Watercool offers two models of each size, named the LT and the Pro. Let’s look at some specs!

MO-RA3 radiator

Watercool external radiator


So what’s the difference between the LT model and the Pro model?  


Fan mounting options

MO-RA3 360

The MO-RA3 360 LT comes with preinstalled mounting brackets on one side that allow installation of nine 120mm fans.

It also includes a separate mount for four 180mm fans.


The MO-RA3 360 Pro doubles these numbers by providing mounting brackets on both sides of the radiator, and including two separate 180mm fan mounts.


MO-RA3 420

The MO-RA3 420 models are set up in almost same way but don’t include the second bracket for larger fans.

The 420 LT can mount nine 140mm fans on one side, while the 420 Pro can mount a total of eighteen 140mm fans.


                    Watercool made in Germany            Custom PC water cooling

Note that while screws are provided with the MO-RA radiators, they are all designed for fans of 25mm thickness.


                             Full external PC water cooling



As impressive as the size and specs are, Watercool’s MO-RA3 system is more than just radiators. Several accessories are available for them that make the radiators much more versatile.



External PC water cooling   Water cooled PC      

For a free-standing installation, feet are available in both acetal and acrylic. Both the 360 and 420 versions use the same feet.


Fan mounts

Both the 360 and 420 versions of the MO-RA3 offer additional fan mounting options.

For the MO-RA3 360 LT, additional fan mounts are available in both 120mm and 180mm sizes, effectively turning the 360 LT into a 360 Pro.


Radiator fans   200mm radiator fans


The MO-RA3 360 Pro comes with all these fan mounting options out of the box – no additional mounts are available.

The larger 420 version of the MO-RA3 has a few more options when it comes to fan mounting.

The same add-on fan mounting brackets as the 360 version are available for the 420 to turn your 420LT into a 420 Pro, but the 420 offers more.

If the stock mounting option of nine (or eighteen for the Pro version) 140mm fans isn’t what you want, a bracket is available for mounting 180mm – 230mm fans. Like all the mounting options, these will fit on either side of the MO-RA3, making it possible to use a huge range of fan sizes.


Custom PC fan mount        Custom PC cooling


Watercool and Noctua – how can you go wrong?

If you’re a Noctua fan, Watercool has you covered with a fan mounting bracket specifically for the Noctua NF-A20 fan. M4 mounting holes and integrated cable routing make mounting these excellent 200mm fans simple.


Noctua 200mm fan          Noctua NF-A20

There’s also an add-on called the X-Splitter for these fans. Essentially a four-port fan hub, the X-Splitter is made to fit neatly into the center of the Noctua fan mount and combines all of the cables from these fans into a single outlet.


Noctua fan cable connector          Noctua Industrial




Watercool has even gone as far as packaging their MO-RA3 420 with the fan mount and made the set available as their MO-RA3 420 for Noctua NA-A20 Fans. This is the only MO-RA3 radiator that doesn’t sport the LT or Pro label as it’s made for specific fans.

Note that while the Noctua version of the MO-RA3 only comes with a single mounting bracket – a second could be added to the other side.


Fan Grills

If exposed fan blades aren’t in your plan, fan grills are available for both sizes of the MO-RA3 lineup.

Fan grills are available in the same materials and colors that are offered for the radiators themselves, and come in two distinct patterns - classic and diamond.

   MO-RA3 classic fan grill    MO-RA3 diamond fan grill

Watercool’s fan grills are designed to cover the entire face of the radiator and mount to premade threaded holes in the frame and can accommodate fans up to 25mm thick.

In addition, the classic-pattern fan grill is available in a higher version made for fans up to 38mm.



Reservoir Mount

          MO-RA3 reservoir mount        Heatkiller Tube mount

If you have a Heatkiller Tube reservoir, this mount (along with the Basic Mounting Kit) will allow you to mount it on either side of the MO-RA3.

Although this mount wraps around the corner of the radiator’s frame it does not interfere with the use of fan grills on either side – an example of Watercool’s dedication to function and form in the MO-RA3 series.


Wall/Case Mount

Available in two separate sizes for each version of the MO-RA3, these mounts allow the radiator to be installed on a flat surface like a wall or case side panel.

Taking the place of the spacers installed on the frame of the radiator, these mounts ensure there is enough space between the radiator and the mounting surface for proper air flow.

Watercool has assured me that the Heatkiller Tube Adapter can still be used with the wall mount installed. The only drawback to this mounting method is that fans cannot be used on the side that the mounts are on.     

MO-RA3 wall mount       MO-RA3 custom mounting solution

Pump Mount

If you want to make your cooling setup as integrated as possible, Watercool also offers a pump mount for the 420. Designed to house two D5 pumps, this mount is made from 1mm thick stainless steel and also includes mounting holes for either a 150mm or 200mm Heatkiller Tube reservoir.

MO-RA3 pump mount        D5 pump housing for MO-RA3

Since this mounting bracket only attaches on one side, it can be used with the wall mount accessory as well.


For The Modders

Watercool hasn’t forgotten about the modders either. Both the 360 and 420 versions of the MO-RA3 are available as bare cores. These come without a frame or fan mounts of any kind.

External water cooling radiator core         MO-RA3 bare core

If you’ve got a design in mind and don’t necessarily want to use Watercool’s stock framing and mounting options, the core version is made for you.




Watercool continues its long history of excellence in both manufacture and materials with the MO-RA3. They’ve seen the need and the demand for good-looking excellent performance outside the case and brought it to us with enough options to please anyone – even the modders.

Like any modular line of products, more add-ons and accessories for the MO-RA3 are likely to see the market. What would YOU like to see in those new products?