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DC-DC Power Supply Guide

 

WHAT IS A DC-DC POWER SUPPLY?

A DC-DC PSU is a small PCB that sits inside your PC instead of a typical ATX or SFX power supply used to power your system.

Pico PSU Example

ADVANTAGES OF DC-DC

The main advantage of DC-DC power supplies is their small size, allowing for more compact and space efficient systems.

Alternatively more of the space in your system can be dedicated to cooling than with an SFX power supply for a more powerful or quieter system in the same amount of space.

Other benefits include silent (fanless) operation of the power supply itself and also higher power efficiency.

 

HOW DO POWER SUPPLIES WORK?

A typical SFX or ATX power supply takes the AC electrical current from your house wall power socket and converts it into a DC current.  The same power supply then separates this DC current into the various voltages required by all the different components of your PC, this is one of the reasons why power supplies have multiple output cables each carrying a different voltage to your different components (motherboard, hard drives, graphics card, etc).

  

HOW DO DC-DC PSU’s WORK?

A DC-DC setup splits the task of a power supply into 2 separate components:  An AC-DC Adapter and a DC-DC distributor, examples of which can be seen below:

1. AC-DC ADAPTER

The AC-DC adapter, sometimes referred to as the “power adapter” or the “power brick” is the rectangular unit you generally find bundled with a laptop or other similar electronics hardware.

It takes the power from your wall socket and converts it into DC current (usually 12V or 19V) which is then passed onto the DC-DC distributor inside the PC/Laptop.

Dell 330w 19v AC-DC Power Adapter

2. DC-DC DISTRIBUTOR

Commonly referred to as a “PicoPSU”, this is a small board that sits inside your system, they often look like rectangular PCBs with capacitors on them.

The task of the DC-DC distributor is to split the DC current provided by the adapter into the different voltages required by your system.  They often have a few different cables with a variety of connectors, an example can be seen below:

 

TYPES OF DC-DC POWER SUPPLIES

There are 2 main types of DC-DC PSU’s that sit inside your computer, they both offer the same function (to distribute power to your components), but are mounted in different ways.

1. DIRECT PLUG

Commonly referred to as a “PicoPSU”, this is the type that plugs directly into the motherboards 24pin ATX power connector.  This type carries a huge space saving advantage as well as much simpler cable management.

Here is an example PicoPSU:

PicoPSU is the brand name, there are also a few other common brands that offer similar “direct plug” style units as well.  A list of the most popular brands and models can be found below including some links of where to buy.

G-Unique

Akasa

Realan

HDPLEX

KMPKT

Usually these require a 12v DC input to provide their power, some models are 19v.

 

2. CHASSIS MOUNTED

This type is typically long and slim in shape, they require mounting points inside the case that match up to the mounting holes on the power board. 

Slim DC 12v power board

Most of these types have a hole spacing of 144mm, but some models differ.  Many different companies make this style of board, they are often bundled with mini PC cases imported from the Far East.  Some popular brands include:

Realan

RGEEK

 

CONNECTORS

An often overlooked area of DC power supplies is the input/output power jacks that connect the AC Adapter and the DC-DC PSU together.  Different brands and models have different types of connectors that can vary in size and shape.  If you are buying your AC Adapter and DC-DC PSU separately then you will need to make sure that they share connectors that are compatible.

Typical male and female “Barrel style” power connectors:

 

VOLTAGES

An important part of planning your DC-DC setup is the voltage output of the AC Adapter and the Voltage input of the DC-DC PSU.   The operating voltage of these 2 parts need to match for them to work together.  The 2 most common voltages are 12V and 19V.

If your not comfortable selecting an AC Adapter and DC-DC PSU that are compatible with each other, the simplest solution is to find a vendor that sells them together as a package.

  

WATTAGE

As with standard power supplies, DC-DC power supplies come in a variety of power ratings (wattage), this applies to both the AC Adapter and the DC-DC Distributor.  The higher the power rating of your DC-DC components the more powerful of a system you can build.

If the wattage is not displayed in the products title or description it can be worked out by multiplying the Amps by the Volts.  For example an AC Adapter that is 12V and 10A has a wattage rating of 120W (12 x 10 = 120).

HOW MUCH WATTAGE DO I NEED?

The required wattage to power your system is often lower than you may think, especially when it comes to Small Form Factor systems and being limited to what you can install.

DC-DC PSU’s can range in wattage anywhere from as low as 60W right up to 400W, a higher wattage unit typically means a higher price tag.  If your system for example only uses 50W in total then a 60W DC-DC PSU will be sufficient, you don’t need to spend more on a higher rated power supply unless you want more headroom for future upgrades.

High quality DC-DC power supplies such as PicoPSU and HDPLEX branded models can safely exceed their wattage rating for short periods of time to cater for spikes in power consumption.

CALCULATING POWER CONSUMPTION

TDP (thermal design power) is the average heat output in watts that a component is creating, this figure can be used to estimate the power consumption of the component at stock speeds/settings.  Total system power draw can be calculated by adding together the CPU and GPU TDP figures, you will also need to include around another 20W for the Motherboard, RAM and storage drives.

For example: A Ryzen 2400G APU has a TDP of 65W, add 20W overhead for the motherboard, storage and RAM and you have an estimated system power consumption of about 85W with stock settings.  Therefore a 120W DC-DC PSU and 120W AC Adapter will be sufficient for this with a little bit of headroom for some mild overclocking.

Another example would be pairing an Intel i3-7100 (51W TDP) with a GTX 1050Ti graphics card (75W TDP) for a total system power consumption of roughly 150W.  For this level of system you may want to select a 160W DC-DC power supply.

 

HDPLEX

Once you start moving up into the territory of high end processors and Graphics Cards the power consumption of your system dramatically increases.  There are a few companies that make high wattage DC-DC power supplies to cater for higher end systems.  HDPLEX is one of them, fast becoming the communities go to choice for high power that require a compact DC-DC style power supply.

HDPLEX 400w HiFi DC-ATX

The 400w HiFi DC-ATX is a high quality chassis mounted 19V DC-DC board.  Its 400w output allow you to comfortably power a high end CPU such as an Intel i7-8700k and a top tier GPU such as a GTX 1080.

Below is an example system using the HDPLEX 400w DC-ATX inside the Lazer3D LZ7  gaming case.  The compact HDPLEX power supply opens up more space for cooling than for example using an SFX power supply would allow:

LZ7 with DC-DC panels, Noctua NH-U9S tower cooler powered by HDPLEX 400w HiFi DC-ATX

HDPLEX AND AC ADAPTERS

The HDPLEX HiFi DC-ATX accepts a 19V DC current, a good match for HDPLEX units are the Dell 19V AC Adapters.  They also share the same style of power jack for simple plug and play compatibility.  Below is the HDPLEX DC-ATX and a Dell 19V 330w AC Adapter:

HDPLEX INTERNAL AC-DC ADAPTER

HDPLEX also offer an internal AC-DC Adapter which can be used in place of the external AC Adapter (Power Brick), this allows you to build what is called a “brickless” system, i.e. the power cable from your wall socket plugs directly into your case as it would with a standard SFX or ATX power supply.

HDPLEX have 80w, 160w and a soon to be released 400w model (shown below):

You do however need to find space in your case for both the AC-DC Adapter and the DC-DC board which can be tricky.  An example of this type of setup can be seen below, both shown inside the Lazer3D HT5 low profile case:

HT5-Stealth-Brickless-with-NH-L12S

HDPLEX Direct Plug 160w NanoATX

HDPLEX also offer a high quality direct plug style 160w DC-ATX Nano power supply, great for low to mid level system with 65w TDP CPU’s and PCIe powered Graphic Card combos such as the GTX 1050Ti:

HDPLEX 160w NanoATX DC-DC Power Supply

LAZER3D CASES & DC-DC PSUs

LZ7 DC-DC PSU and Tower Cooler Setup

For more detailed information on using DC-DC power supplies with Lazer3D products please click the relevant links below:

Lazer3D LZ7 DC-DC GUIDE

Lazer3D HT5 DC-DC GUIDE

 

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