Removing and reusing Wi-Fi/Bluetooth modules from modern single-board PCs

In mid-80’ IBM PC brought us a versatile and easily reconfigurable hardware computer architecture that we are still using today. Unfortunately, this architecture is slowly getting shadowed by single- board computer architectures, like mini PCs and laptops that have a very few configurable components. The only user replaceable components in the majority of newest mini PCs and laptops are mass data drives and memory modules. Replacing other components requires technical skills and good understanding of a particular single-board computer architecture.

Are Wi-Fi/Bluetooth modules potential security holes?

Why would anyone want to remove a Wi-Fi/Bluetooth module from a mini PC or a laptop? Many computer safety experts are concerned about ever more sophisticated hacker attacks on information systems in private enterprises and companies. Usually, it is the weakest link that enables them to gain access to a company’s internal computer network and a Wi-Fi/Bluetooth module in a laptop or a mini PC in an office is certainly one of them. 

Though a Wi-Fi/Bluetooth module may be programmatically turned off in BIOS and in the operating system there is still no guarantee that some malicious software would not succeed turning it back on and somehow enabling a hacker to establish a connection from a nearby parked car or a building. 

Many computer manufacturers had foreseen such a possibility in the past and had allowed for Wi-Fi/Bluetooth modules to be removed from their laptops and mini PCs by authorized computer technicians. However, as laptops and mini PCs were getting cheaper adding a special connector and a mini raiser board with a Wi-Fi/Bluetooth module started becoming an issue. Many manufacturers instead added enhanced software protection to their computers BIOS and omitted Wi-Fi/Bluetooth removal options. However, with new hacking tools there may still be a remote possibility of a successful hacker Wi-Fi attack. Can we still remove or replace Wi-Fi/Bluetooth module?

Will my computer work without a module? 

If a Wi-Fi/Bluetooth module is not meant to be removed by the manufacturer, there is always a remote possibility that its removal could prevent computer from booting normally. Luckily, most computers have a modular BIOS that easily adapts to a non-crucial module removal, or even treat a Wi-Fi module as an external module operated exclusively by an operating system. Removing the module usually only means less connectivity, but it usually does not impede other computer functionality.

Removing attached and soldered-on modules

Almost all older laptops and mini PCs have removable Wi-Fi modules on raised boards that are plugged into special connectors on their mainboards. A skilled computer technician is able to remove or install them in about half an hour. Removal of a Wi-Fi module usually requires dismantling and reinstalling other components like: keyboard assembly, lithium batteries, DVD drives, SSDs, cooling system etc., but no soldering is needed.

Newer mini PCs and laptops Wi-Fi/Bluetooth modules are soldered or even glued to their mainboards. Most of the modules are connected to the mainboards through internal USB ports, which greatly simplifies a mini computer design and requires much less wired connections from a module to a mainboard. Less contacts enables quicker and easier unsoldering, but removing a glued Wi-Fi/Bluetooth module may still pose a challenge. 

The modules are built on mini PCBs that are usually smaller than 3 cm x 3 cm. They can usually be removed from mainboards without causing any damage to a mainboard or a module, but a lengthy procedure requires precise work and skills. However, the general advice here is just to be cautious and to think each step twice to avoid damaging the mainboard or the module.

Can I just cut some of the module connections to the mainboard to disable it?

Yes, and no! It may be practical to leave a Wi-Fi/Bluetooth module in-place and just cut some of its connections to the mainboard to disable it, but this requires a detailed understanding of the module pin layout and operation. For Wi-Fi/Bluetooth modules that connect to the mainboard through an USB connection it generally suffices to cut data lines (D+ and D-) to physically prevent the module configuration and operation.

Replacing an inbuilt module with a newer one

There is usually no difference for a computer programmer between an externally connected Wi-Fi/Bluetooth module that connects through an USB port and internal one. However, internally connected USB devices need no protection on their USB data lines as they are also connected to the computer internal power supply. 

It is possible replace an inbuilt Wi-Fi/Bluetooth module with a newer one if the following conditions are met: (1) its power consumption is roughly the same, (2) it uses the same version of USB (ex. USB 2.0), (3) it has the same pin layout, or it is possible to make a small enough adapter, (4) it uses the same type of antenna, and (5) there is a suitable device driver available for our operating system.

Can a removed Wi-Fi/Bluetooth module work with other computers?

Yes, if the module is undamaged and if it is possible to obtain a complete documentation and device drivers for it. Most of the extracted modules also need a +3.3 V power supply, so a voltage regulator from +5 V (Vbus) to +3.3 V also must be implemented, if we intend to use the module as an external USB device. A new Wi-Fi antenna may also be needed, if we have not extracted it from the donner computer as well.

Does it work?

Yes! I extracted a Wi-Fi module from various computers and so far it has always worked flawlessly. Older laptops just have to be carefully disassembled to be able to reach the Wi-Fi/Bluetooth card, newer computers such as Banana Pi-R1 and many mini PCs, must have their Wi-Fi/Bluetooth module that connects to the internal USB 2.0 bus unsoldered. 

I was even able to reuse an extracted Realtek RTL8821CU module from a mini PC in an external USB 2.0 communication device by adding a +3.3 V voltage regulator, an external Wi-Fi/Bluetooth antenna and a USB 2.0 cable. The module now works with a number of PCs and even with a Raspberry Pi 3 and a Raspberry Pi 4, provided that a device driver for the installed operating system is available.