Current notable computer hardware manufacturers:

Cases

List of computer case manufacturers:

Rack-mount computer cases

Laptop computer cases

Motherboards

Top motherboard manufacturers: List of motherboard manufacturers: Defunct:

Chipsets for motherboards

Central processing units (CPUs)

Note: most of these companies only make designs, and do not manufacture their own designs. Top x86 CPU manufacturers: List of CPU manufacturers (most of the companies sell ARM-based CPUs, assumed if nothing else stated):

Hard disk drives (HDDs)

Internal

List of current hard disk drive manufacturers:

External

Note: the HDDs internal to these devices are manufactured only by the internal HDD manufacturers listed above. List of external hard disk drive manufacturers:

Drive controller and RAID cards

Solid-state drives (SSDs)

Many companies manufacture SSDs but there are only a few major manufactures of NAND flash devices that are the storage element in most SSDs. The five major NAND flash manufacturers are:

Optical disc drives (ODDs)

List of optical disc drive manufacturers:

Fans

Fan controllers

Computer cooling systems

List of computer cooling system manufacturers:

Non-refillable liquid cooling (AiO)

List of non-refillable liquid cooling manufacturers:

Refillable liquid cooling kits

List of refillable liquid cooling kits manufacturers:

Water block

List of water block manufacturers:

Video-card cooling

List of graphics card cooling manufacturers:

Computer monitors

List of companies that are actively manufacturing and selling computer monitors:

Smartglasses

Virtual reality headsets

Video cards (graphics cards)

List of video card manufacturers:

Graphics processing units (GPUs)

Keyboards

List of keyboard manufacturers:

Mouse

List of mouse manufacturers:

Joysticks

List of Joystick manufacturers:

Speakers

List of computer speaker manufacturers:

Modems

List of modem manufacturers:

Network interface cards (NICs)

List of network card manufacturers:

Chipsets for network cards

There are a number of other companies (AMD, Microchip, Altera, etc.) making specialized chipsets as part of other ICs, and they are not often found in PC hardware (laptop, desktop or server). There are also a number of now defunct companies (like 3com, DEC, SGI) that produced network related chipsets for us in general computers.

Power supply units (PSUs)

List of power supply unit (PSU) designers:

Random-access memory (RAM) modules

Note that the actual memory chips are manufactured by a small number of DRAM manufacturers. List of memory module manufacturers:

Random-access memory (RAM) chips

List of current DRAM manufacturers: List of former or defunct DRAM manufacturers: List of fabless DRAM companies: In addition, other semiconductor manufacturers include SRAM or eDRAM embedded in larger chips.

Headphones

List of headphone manufacturers:

Image scanners

List of image scanner manufacturers:

Sound cards

List of sound card manufacturers:

TV tuner cards

List of TV tuner card manufacturers:

USB flash drives

List of USB flash drive manufacturers:

Webcams

List of webcam manufacturers: