What Does a PSU Do in a Gaming PC?

Power supplies or PSUs are arguably the most important component to be maintained in a PC. If performance were a carefully crafted sculpture, the PSU would be the clay.

PCs require massive accuracy when dealing with power conversion from AC/DC, provide clean power to the system via MOSFETs, or metal oxide semiconductor field effect transistors, and ensure the system is safe to perform. In this article, we cover the conventional data for current-gen power supplies and the next generation of power supplies in what we know. 

What is a Power Supply?

A Power Supply Unit (PSU) is a mediation component responsible for converting AC current from a wall outlet into both lower AC and DC voltages safe for PCs to use. Essentially, a PC's power supply unit is what provides power to your system.

Each type of power supply is different in its design and certification and offers a wide range of supported voltages for multiple types of different hardware.

Things to Consider in a PSU

While PSU for PCs serves the same purpose, there are many categories and build qualities with PSUs. Terms like “80+ Certified”, “Non Modular”, “Passive cooling”, and “SFX” are all terms used when describing the types of power supplies for systems with specific characteristics and hardware. We at Apex have devised a comprehensive list of the majority of terms used to define retail power supplies along with explaining what PSUs we use to ensure the life of our prebuilt gaming PCs.

Wattage

Wattage is the power available to a system from a given component. Every piece of hardware has a given power limit at a specific Wattage that contributes to the total draw of the system. Let's create an example system so we can see where the wattage goes into:

As seen above the CPU and GPU take the most amount of wattage followed by the motherboard and other accessories in gaming PCs. Wattage is important as it best describes the budget of a given set of components.

These estimates are also non-static as power spikes from components are typical and must be budgeted when choosing the right PSU for the system.

Typically, having a PSU around 100 watts above the total system usage will be enough to facilitate the PC's needs. However, depending on the efficiency of the PSU, they will often have a more challenging time providing the proper power delivery if the power requirement is near the limit of their advertised wattage.

Let’s explore the pros and cons of wanting to future proof a PSU to last for however long a given system’s power input will be. 

PSU Efficiency Curve

The PSU efficiency Curve is an essential indicator of a PSU performance under load. With terms like “80+ Plus rating,” each given power supply can convert over 80% of its power into usable electricity for the system; the rest turns into heat.

Here is a graph showing the usability and efficiency of PSUs courtesy of an article by Corsair:

The graph above shows the efficiency of a 750W Corsair power supply and its results under load. The red line represents the performance with 115V of wall input (USA) and the blue represents the 230V of wall input (EU). While a higher voltage can generate more performance, it almost always comes at the cost of cooling.

Power supplies are at their peak efficiency 45-50% under load with this data. The system we designed above would need a 1000W PSU to become optimized for power delivery. This is not considered for a majority of systems, as having enough headroom ensures healthy operation of the PC for around five years.

Form Factor

From factors are popular in their designs as they allow for a multitude of different types of systems to become viable in their power delivery. There are four (three if you don't count revisions) main form factors of power supplies that serve a multitude of systems:

ATX:

The ATX (Advanced Technology Extended) platform is the most common type of PC component standardized in 1995. With this new generation of components, PSUs grew into this categorization. They offered multiple upgrades, moving from 20 PIN connectors to 24 PIN connections, among other incremental upgrades as power supplies developed over the years.

ATX12V: 

This type of revision goes unnoticed primarily in the consumer gaming market. In recent years, updates to how the PC better facilitates spikes, power consumption, and efficiency. You can usually spot the specific compliance version with some retailers.

SFF:

SFF or Small Form Factor is a diminutive form of an ATX configuration power supply with more streamlined connections due to space. These are power supplies that require a lot less space to function. In recent years, SFF has had a resurgence in new technology applied to the form factor that PSUs up to 1000W can be viable.

EPS12V:

EPS is a non-ATX associated PSU platform meant for Server System Infrastructure (SSI). While these can be retrofitted to lower-end office systems, EPS PSUs are not recommended for any mainstream gaming systems due to their loud fan noises and lackluster support for mounting in modern ATX gaming towers. 

Cable Management

Power supplies come in three different wire configurations for the end-user. Depending on a multitude of factors like price, intended use, and space, there is a wire configuration for every occasion.

Non-modular: 

Non-modular is for cables integrated into the PSU and cannot be removed. Due to this trait, they need to be stored in the compartment housing the PSU. This can be a deal-breaker, depending on how accommodating the space is.

Semi-Modular:

Semi-Modular is a hybrid of non-modular. Significant connections like the PSU(24PIN, CPU 8 PIN, GPU 8 PIN) are mandatory; however other connections like SATA and MOLEX are optional.

Fully-Modular:

Fully Modular are customized to the greatest extent, with every connection for a system needing to be plugged into the power supply.

Heat Management

Heat management for PSUs is standard as each ATX version of PSU is fitted with a 120MM or 140MM Fans cooling. The performance on cooling depends on how the airflow of the case is configured; however, more often than not, this build variation has proven resilient for this design.

Noise 

With the occasional occurrence of coil whine in newer components, noise from PSUs should be minimal as the silent operation is a key feature for PSUs. If any creaking or buzzing can be heard from the PSU chassis then a bad fan bearing could be the issue.

Voltage Stability  

While PSUs are under load, the connected hardware can engage in “spikes” that cause the PSU to draw more power than needed for a few milliseconds. Voltage stability is needed to ensure a PSU does not trip its safety features for overdraw and shut the system off. These events are less common depending on the number of Watts the system draws and overall build quality.

Aesthetics

While PSUs are preferred for function over form, gaming-centered PSUs have not failed to make a mark in the market. Some case designers have intentionally left a hole in the PSU shroud of a given case to show off stylized branding from PSU companies, not to mention RGB PSUs. While not necessary, companies like ASUS and their ROG series with digital wattage indicators certainly show off!

How to Check Your PSU

To check what type of PSU is in a system, the only reliable way is to open up the system and check the side of the PSU casing. Open the side panel of the PC and look at the rated wattage and 80+ certification. If one is not visible from the open panel side, it will most likely warrant the removal of the PSU to see the other side.

New PSU’s Power Requirements on the Horizon

Just recently, the NVidia related more information on the 3090 ti and the Architecture for the 4000 series being AD-103 with impressive performance gains over the previous generations at almost double the power requirement.

This new standardization of power requirements comes with new adaptors for PSUs looking to get the latest hardware on the market.

With this major change in GPU power requirements, average GPUs need power requirements of 600W-850W for any high-end GPU with this new 24 to 12 pin connection.

What This Means For GPUs in 10 Years

With power requirements ever-rising for GPUs and CPUs, PCs need a higher-end PSU to take on the demands of ever increasing hardware. While this may apply to the upper echelon in computer gaming to get the absolute best system, gaming on a budget for both money and power will not disappear anytime soon.

Apex’s recommendation for PSUs: 

Most systems' life spans for components are around five years to fall off the pinnacle of gaming. A PSU can outlive all components in a given system for up to eight to ten years. When choosing one of our Custom Gaming PCs,  it's essential to ask if an upgrade is in this system's future. Depending on how long a system is in operation, the PSU may or may not be able to handle future upgrades. No matter the size or function, the most crucial function of a PSU is its available voltage and adaptors to hardware. Whatever your future plans for PSUs, we hope to support them at Apex!

Written By William Wilson