To make customize computer system from computer components, you need at least 6 computer parts named Motherboard, Processor, RAM, Hard Disk and Power supply(PSU).
Here is the details why you need this computer components.

Desktop Computer Motherboard
Above picture is a Desktop computer motherboard. This motherboard helps you to connect others computer parts together.
1. Computer Processor Slot: Number one in motherboard is a processor Slot. Processor in desktop computer works like human brain. You have to place your computer processor in this slot. The processor looks like below picture

Computer Processor
Note: when you are placing your processor in motherboard, don’t forget to put a cpu cooler fan above the processor.
2. RAM Slot: Number two in motherboard picture is a RAM slot. RAM works like human blood. There are 3 kinds of RAM for Desktop and Laptop Computer in Market for normal computer user. They are DDR1, DDR2 and DDR3 Memory. Computer RAM looks like below picture

Desktop Computer memory
3. SATA Connection Slot: Number three in motherboard picture is for SATA connection. Most of the recent desktop computer motherboard support SATA connection for Hard Disk Drive and Optical drive. SATA Hard Disk looks like below picture

Desktop Hard Disk
4. Power Supply Unit (PSU) : Number four slot in motherboard using for power supply unit connection. This power supply unit slot helps to supply power in desktop computer motherboard. For general user you can use 500-600 watt Power Supply Unit.
PSU look like below picture

PSU
5. PCI Slot (EXTRA) : Number five in motherboard is a PCI Card Slot. PCI card slot helps you to use extra Graphic Card. PCI Graphics card is look like below picture

PCI Slot
6. Computer Case : You can use your custom made computer without computer case but you need to be expert on how to do this. Computer case helps you to keep whole motherboard, hard disk, optical drive together. And it is also safe to use computer case from getting hardware damage and electricity shock.
The Desktop Computer Case look like below picture

Desktop Computer Case







