First Watercooling Loop

Pumps

There are two main established pumps used in watercooling – the DDC style and the D5 style. Both are well established for a reason, and if in doubt I would choose one of these two types. Cheaping out on a pump can be money thrown away, but both DDC and D5 style pumps are well respected in that they don’t have a high failure rate and have decent pumping power, price and noise.

So let’s ignore all other pumps than the DDC and D5 simply because this is a beginner’s guide! Generally speaking the DDC is more compact and the D5 is a little quieter. My preference is the D5, it’s solid, reliable and doesn’t get hot. There are variants of each that are often rebranded. Let’s start with the D5:

The Laing D5 or MCP655 series

The D5 typically comes looking like this:

This version has the default Laing top and lockring fixed to it. You can however order a “bare version” like this alphacool 655-B:

This bare version will need a “top” added to it. Bear in mind some tops require you to have the default Laing o-ring and lock-ring in order to use them, so ordering the bare version may get you into trouble if you need those parts.

The default Laing top of course only fits one size of tube. It’s designed to fit 1/2″ ID tube over the end. With a bit of stretching 7/16″ ID tube will also work. If you want to run any other type of tube, you’ll either need a top, or a version that has been tapped to accept fittings. For now we will ignore all the tops and just focus on the motor control.

There are 5 main varieties of D5:

Basic – one speed no adjustability, no tachometer wire to tell pump rpm (useful to know whetter the pump is dead).
Vario – this is the most commonly bought version – it has a little analog dial on the back that can change pump speed. Setting 4 is most commonly used as a good blend of power/noise
PWM – this is relatively new, speed can now be controlled by a PWM control signal which can be plugged into a motherboard header or PWM compatible fan controller and will enable automatic pump speed control
USB – Aquacomputer made a usb version of the D5 where the Aquacomputer software can control speed over a USB connection to the pump. With the release of the PWM pump and the Aquaero 6, there is not much point in buying this
D5 Strong or PMP450s – Koolance introduced the PMP450s which is essentially a D5 with a higher top end rpm. The higher rpm translates to more pumping power, but it gets hotter and noisier and requires a 24V controller

We would recommend either the D5 vario or the D5 PWM depending on if you’re a “set and forget” type of person or a “optimization of noise for different heat loads” type of person.

If you wish to use different tube to 1/2″ and do not want a built in reservoir then I would strongly consider getting a top. They look better and have a slight performance improvement. Koolance, XPSC and EK all make good tops for the D5. More on built in reservoirs later…

The Laing DDC or MCP35* series

The DDC pump is a little more compact than the D5. A lot of the models now come with tops pre-attached, but again the Laing top doesn’t take fittings and instead takes tube:

(Photo shamelessly stolen from PPCs). These Laing tops only take 8 or 10mm ID tube (3/8″ is roughly 10mm) so again for future proofing you may want a top anyway, but first let’s discuss motor options.

Obsolete parts:
DDC-1
DDC-1T
DDC-1T Plus
DDC-2
Current Parts:
DDC-3.1 some people claim this is also the MCP350
DDC-3.15 some people claim this is also the MCP350
DDC-3.2 some people claim this is also the MCP355
DDC-3.25 some people claim this is also the MCP355 and PMP400
MCP35x

Did that confuse you? It certainly confused me. I haven’t used all the DDC pumps, however I do use the MCP35x in my day to day testing rig and so this is the one I’d recommend. It also has everything you would need. It has PWM, a fitted head that can accept fittings and has tons of power that can easily be turned down with PWM control.

Again this might change if you are buying a reservoir to directly mount the pump to.