L1, L2 is two levels of cashe memory in computer .

A CPU cache is a cache used by the central processing unit of a computer to reduce the average time to access memory. The cache is a smaller, faster memory which stores copies of the data from the most frequently used main memory locations. 

using two level cashe memory – may be more than two – save time compared to
having to get it from random access memory .

L1 : is that first level inside the microprocessor chip very fast in processing .

L2 : is separated in outer chip less speed than L1 but still faster  than RAM  .

so increasing  cashe levels will increase  processing speed and so our pc performace .

Why not just have a big L1 cache? The L1 cache is extremely expensive.
So the L1/L2/L3 system makes for great (not optimal, if you had a
really big L1 cache it’d be faster) performance that doesn’t cost an
arm and a leg.

A motherboard =  central printed circuit board (PCB) =  mainboard =  system board =  Applelogic board = mobo.

The motherboard’s main job is to hold the computer’s microprocessor
chip and let everything else connect to it. Everything that runs the
computer or enhances its performance is either part of the motherboard
or plugs into it via a slot or port.

The essential motherboard make-up includes the chipset (known as the “glue logic“), some code in ROM and the various wired interconnections between the components know as buses.
The chipset is fundamental, and controls how the motherboard interacts
with everything else in the system. A good chipset can be more
important than the power of CPU or the amount of RAM. The ROM code
includes the BIOS, which has user-changeable options for how the
motherboard operates with integral and connected devices.

 Motherboard Standard  :

1-Form factor is the shape and layout of a motherboard ,The form factor affects where individual components go and the shape of the computer’s case.

2-  Socket for the microprocessor determines what kind of Central Processing Unit (CPU) the motherboard uses.

3- The chipset is part of the motherboard’s
logic system and is usually made of two parts — the northbridge and
the southbridge. These two “bridges” connect the CPU to other parts of
the computer.

4- (BIOS) chip controls the most basic functions of the computer and
performs a self-test every time you turn it on. Some systems feature
dual BIOS, which provides a backup in case one fails or in case of
error during updating.

5-The real time clock chip is a battery-operated chip that maintains basic settings and the system time.

The slots and ports found on a motherboard include:

1- (PCI)- connections for video, sound and video capture cards, as well as network cards

2-Accelerated Graphics Port (AGP) – dedicated port for video cards.

3-Integrated Drive Electronics (IDE) – interfaces for the hard drives

4-Universal Serial Bus or FireWire – external peripherals

5-Memory slots

The clock speed that the component is rated for is at or below the speed at which the CPU has passed the manufacturer’s functionality tests when operating in worst-case conditions (for example, the highest allowed temperature and lowest allowed supply voltage)

overclocking is the process of running a computer component at a higher clock rate than it was designed for or was specified by the manufacturer.

Overclocking a computer’s processor or memory causes it to go faster than its factory rated speed. A processor rated at 2.4GHz might be overclocked to 2.5GHz or 2.6GHz, while memory rated at 200MHz might be pushed to 220MHz or higher. The extra speed results in more work being done by the processor and/or memory in a given time period, increasing the overall computing performance of the PC.

The most obvious reason to overclock a computer system is to squeeze some additional performance out of it at little or no cost. Overclocking the processor and system memory can significantly boost game performance, benchmark scores and even simple desktop tasks. Since almost every modern processor and memory module is overclockable to at least a slight degree, there are few reasons not to attempt it.

most important considerations for overclocking :

Heat :

The faster a computer goes, the more heat it produces. This is especially true when the voltage being fed to certain components is increased, a standard overclocking method. Excess heat in the processor, motherboard chipset or memory can cause crashes and system instability, and may be one of the limiting factors in determining the maximum overclock for a system so we need more cooling when overclocking

Power Supply :

Overclocking a computer system also increases the amount of power it draws, and this may lead to system instability if its old 300Watt power supply is not up to the task. If overclocking a modern Pentium 4 or Athlon 64 system, plan on upgrading the power supply to at least 400Watts