So you've picked up a prebuilt gaming PC and it's been doing the job, but now it's starting to struggle. Frames dropping, load times dragging, or maybe you just want to push into higher settings. Whatever the reason, upgrading a prebuilt is one of the smartest moves you can make, and it's far easier than most people assume.

This guide walks you through the whole process, from knowing what to upgrade first, to actually getting the job done, no tech degree required.

What Is a Prebuilt Gaming PC?

A prebuilt gaming PC is a desktop computer that comes fully assembled and ready to use straight out of the box. Unlike a custom build where you choose and fit every component yourself, a prebuilt is put together by a manufacturer or retailer, everything from the CPU and GPU to the RAM and storage is already installed and tested.

They're a popular choice for anyone who wants to get gaming quickly without the hassle of building from scratch. Whether you're looking at a cheap prebuilt gaming PC for casual play or one of the best prebuilt gaming desktops for high-performance titles, they all share one great quality, they can be upgraded over time.

Can You Actually Upgrade a Prebuilt Gaming PC?

Yes, absolutely. Most prebuilt gaming PCs use standard components that can be swapped out just like any custom build. There are a few exceptions, some budget machines use smaller form-factor cases or proprietary motherboards that limit your options, but the vast majority of prebuilts on the market today are upgrade-friendly.

Before you spend a penny, take five minutes to check what's inside your machine. You can do this by:

• Pressing Win + R, typing dxdiag, and hitting Enter

• Using free tools like CPU-Z or Speccy

• Checking the original spec sheet from where you bought it

Once you know your current specs, you can plan your upgrade path properly.

What Should You Upgrade First on a Prebuilt PC?

This is the question most people get wrong. They go straight for the GPU when the bottleneck is actually somewhere else. Here's the order that makes the most sense for the majority of gamers:

1. RAM (Memory)

If your machine has 8GB of RAM, upgrading to 16GB is the single quickest win you can get. Many budget prebuilt gaming PCs ship with just 8GB, which is genuinely not enough for modern gaming. Games like Call of Duty Warzone, Microsoft Flight Simulator, and even Minecraft modpacks will run noticeably better with 16GB or more.

What to check: Your motherboard's maximum RAM capacity and whether your slots are already full. If you have two sticks of 4GB, you can swap them for two sticks of 8GB (dual-channel matters, always buy in pairs).

Rough cost in the UK: £30–£60 for a quality 16GB DDR4 kit.

2. Storage (SSD Upgrade or Addition)

If your prebuilt came with a mechanical hard drive (HDD), swapping it for a solid-state drive (SSD) will make it feel like a completely different machine. Boot times, game load screens, and general responsiveness all improve dramatically.

Most modern prebuilts include at least one M.2 slot on the motherboard, which means you can add an NVMe SSD without even needing to remove the existing drive.

What to check: Does your motherboard have a spare M.2 slot? If not, a 2.5" SATA SSD is still a solid upgrade.

Rough cost in the UK: £50–£80 for a 1TB NVMe SSD from brands like Samsung, Crucial, or Kingston.

3. GPU (Graphics Card)

The GPU is what does the heavy lifting for gaming. If you're sitting on an older mid-range card — something like a GTX 1660 or RX 580, upgrading to a newer generation card will give you a significant jump in performance, especially at 1080p or 1440p.

This is also the most expensive upgrade, so it's worth waiting until you've squeezed everything out of your RAM and storage first.

What to check: Your case size (will the new card physically fit?), your PSU wattage (can it handle a more powerful GPU?), and whether your CPU will bottleneck the new card.

Rough cost in the UK: £200–£500+ depending on the card.

4. PSU (Power Supply)

If you're upgrading your GPU, your power supply might need to come along for the ride. Many cheap prebuilt gaming PCs ship with a PSU that's just about adequate for the stock components, adding a more power-hungry graphics card can push it over the edge.

Check the wattage on your current PSU and compare it to the recommended wattage for your new GPU. A good rule of thumb is to have at least 100W headroom above the GPU's TDP, accounting for the rest of the system.

Rough cost in the UK: £60–£120 for a reliable 650–750W unit from Corsair, be quiet!, or Seasonic.

5. CPU Cooler

Stock coolers that come with prebuilts are functional but often leave performance on the table. If your CPU is running hot and you want a bit more headroom — especially if you're doing any light overclocking, swapping to an aftermarket cooler is a low-cost improvement.

Rough cost in the UK: £25–£60 for an air cooler; £80–£150 for an AIO liquid cooler.

Step-by-Step: How to Physically Upgrade Your Prebuilt

Tools You'll Need

• Phillips-head screwdriver (magnetic tip makes life easier)

• Anti-static wrist strap (optional but recommended)

• Thermal paste (if replacing the CPU cooler)

• A clean, flat surface

Step 1: Power Down and Disconnect Everything

Turn off your PC completely and unplug it from the wall. Don't just put it in sleep mode — fully power it off. Disconnect the monitor, keyboard, mouse, and any peripherals.

Step 2: Open the Case

Most prebuilt cases use thumbscrews on the side panel. Remove these and slide the panel off. If yours has clips or other fasteners, check your manual. Take a moment to look inside and get familiar with the layout before touching anything.

Step 3: Ground Yourself

Static electricity is the enemy of PC components. Touch a metal part of the case frame before handling anything. If you have an anti-static wrist strap, clip it to the case.

Step 4: Install Your New Component

• For RAM: Release the clips on either end of the slot, line up the notch on the stick with the slot, and press down firmly until both clips click into place.

• For an SSD: Slide the M.2 drive in at an angle, push it flat, and secure it with the single screw.

• For a GPU: Remove the old card by unscrewing it from the rear bracket and releasing the PCIe clip. Insert the new card, screw it in, and reconnect the power cables.

• For a PSU: Unplug all existing cables, remove the old unit, slot the new one in, and reconnect everything. Follow a cable management guide if you're unsure which cables go where.

Step 5: Close Up and Test

Reattach the side panel, plug everything back in, and power on. For RAM and SSDs, Windows should detect them automatically. For a new GPU, download the latest drivers from Nvidia or AMD's website before running any games.

Is It Worth Upgrading a Prebuilt?

In most cases, yes, especially if the core components (CPU and motherboard) are still decent. Spending £100–£200 on RAM and an SSD can extend the life of a prebuilt by two or three years and make a genuine difference to your gaming experience.

That said, there comes a point where upgrading becomes more expensive than simply investing in one of the best prebuilt gaming desktops available today. If you're looking at replacing the CPU, GPU, and PSU all at once, it might be worth comparing that total cost against a fresh prebuilt that already has everything you need.

If you're in the market for a new machine and want to see what's worth buying right now, have a read through the Top 7 Pre-Built Gaming PCs in 2026, a solid breakdown of the best options available in the UK this year, across different budgets.

FAQs

What is a prebuilt gaming PC? 

A prebuilt gaming PC is a fully assembled desktop computer built and tested by a manufacturer, ready to use out of the box without any self-assembly required.

Can you upgrade a pre-built gaming PC? 

Yes, most prebuilt gaming PCs support standard component upgrades including RAM, storage, GPU, and PSU, just like a custom-built machine.

What should I upgrade first on my prebuilt PC? 

Upgrade RAM to 16GB first, it's the cheapest and most impactful change, especially if your machine ships with only 8GB.

How do you upgrade a gaming PC? 

Power it off, open the case, install your new component (RAM, SSD, or GPU), close it up, and boot into Windows to install any required drivers.

What is the average lifespan of a prebuilt PC? 

A mid-range prebuilt lasts 3–5 years without upgrades. With upgrades to RAM, storage, and GPU, you can extend that to 6–8 years comfortably.

How to update a PC step by step? 

Identify what needs upgrading, buy compatible parts, power off and open the case, install the new component, and boot up to configure drivers or settings.