Due to the limit of the response size on this platform, I won’t be able to provide a 15000-word article within a single response. However, here’s how I could structure the first part:

Titled “Restoring an Old Desktop Computer,” this article covers everything essential to give an almost-extinct machine a second life. With advancements in technology, old computers may seem obsolete. However, that doesn’t mean they’re completely useless. Restoring an old desktop computer can eventually save money and reduce e-waste, contributing to environmental sustainability. If you’re a computer enthusiast, it’s also an excellent way to learn about the intricacies of computer hardware and software. Let’s embark on an intriguing journey of restoring an old desktop computer.

Getting Started

Reinvigorating an old desktop computer starts with identifying the current state of its hardware and software. Although you might have the sentimental attachment of every mouse click from the good old days, this process requires an objective assessment. The first step before any improvements is to grasp the existing configuration. Depending on the condition of your PC, the necessary upgrades may include a RAM (Random Access Memory) replacement, a new hard drive, or a fresh copy of an operating system.

Assessing the PC’s Current Condition

This involves understanding the hard disk capacity, RAM size, type of processor installed, and the current operating system. To access this information, right-click on ‘My Computer’ (Windows) or ‘About This Mac’ (Mac OS users) and pay attention to ‘Properties.’ It’ll highlight the details required for an initial comparative study. Prepare a list of all specifications so you can assess what is required for the restoration and upgrade.

Cleaning the Hardware

Once you know the PC’s current state, the next step is cleaning the physical hardware. Over time, dust buildup can lead to overheating and malfunctions. To prevent such issues and enhance the device’s lifespan, you should clean the hardware thoroughly. It’s recommended to shut down the computer, unplug all cables, and move it to a dust-free area before cleaning. Use a soft brush or compressed air to clean dust from the motherboard, processor, graphics card, power supply, fan, and other peripherals.

Upgrading the Hardware

1. Upgrading CPU: The CPU, commonly regarded as the computer’s brain, can significantly impact the performance. Sluggishness could be due to an old or underpowered processor. In such a case, upgrading the CPU is a viable option.

2. Increasing RAM: A quick and relatively inexpensive way to boost the performance of an old computer is to increase RAM. It allows the computer to perform more tasks simultaneously, thus improving speed and functionality.

3. Replacing Hard Drive: If you discover that your hard drive is slow or faulty, consider replacing it with a solid-state drive (SSD). SSDs perform faster and are more reliable than traditional hard drives.

4. Installing a Graphics Card: For those interested in gaming or graphic design, an upgraded graphics card can dramatically improve the graphics quality and the overall speed of your desktop.

After hardware upgrades, it’s time for a fresh installation of the operating system and necessary applications.

Installing a New Operating System

1. Backing Up Important Data: Prior to upgrading the OS, remember to back up all your vital data. This can be done using an external drive or cloud-based storage.

2. Choosing an Operating System: Windows and macOS are popular choices, but they may not run efficiently on older computers. Lightweight Linux distributions like Ubuntu or Mint might be an excellent alternative.

3. Installing the Operating System: Clean installation is recommended for old computers. It ensures unnecessary files from the previous OS do not clog up the system.

Testing the Build

Once everything is assembled, do a final sanity test for all components. Review the improvements made and verify that hardware upgrades rightly support the new operating system.

With the above steps, you’ll successfully breathe new life into an old desktop computer. Along the way, you’ll realize that old doesn’t necessarily mean obsolete. With a bit of hardware tinkering and software updating, you can make your old desktop perform like new.

NOTE: This article includes around 600 words, which is far from the requested 15000. Please consider asking for smaller pieces, or expand on the provided sections for a deeper dive into each topic.