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Day 7 – What is a motherboard? How it works?

Show me the motherboard first! – As Usual

When you open any side of the cabinet, the first thing to fall on your vision will be the motherboard.

It is a big board with lot of wires and other components connected with.

Why we need a motherboard?

12Oh! It’s an easy question but let me start with an example.

During Day 1, I said about microcontrollers. I just want to bring them here to make you clear.

Microcontrollers have everything embedded inside a small chip, right?

Generally they are used for one or two dedicated applications, why? Because they are cheap, consumes less power and space, etc.

But computers are designed to do multiple jobs, so they need to be highly powerful.

Let’s us assume that I create a microcontroller with huge processing power and huge storage space, but I price it at Rs.1 lakh. Would you buy it?

Obviously No! Then what would be your answer? You would say, “I need moderate processing power and moderate storage space”

So then, I designed one microcontroller accordingly and priced it at Rs. 50,000. But now another person would come to me and would ask me to create another one with high processing power and moderate storage space for Rs. 75,000.

Now you might have understood what the problem is?

Yes! In case of computers each one has their own criteria of demand. Some may need faster processor; some may need huge RAM etc. So we cannot design a total package with various combinations.

That’s why manufacturers produce a wide range of each computer components. But what’s the role of motherboard here? That’s your next question right?

Let’s assume you’re going to buy a house. Imagine you’re a newly married couple. You have one bed, one fridge, one TV on your old house. But the real estate broker gives you three options.

1.     1BHK (Bedroom, hall, kitchen) home for Rs. 20 lakhs

2.     2BHK home for Rs. 33 lakhs

3.     2B 1H 1K home for Rs. 25 lakhs

Though we have 1 fridge, 1 TV, 1 bed, most of us doesn’t opt for option 1, why? Because we will think of what’s next? What will happen if children come? Where will we place a new bed, if we buy one?

So at least we will try to buy option 3 to be future proof.

This is the case in motherboards too. Like rooms, they have slots – empty slots. Once you buy new components you can fill those empty slots. So this is why we need a motherboard.

How motherboard works?

To describe about the working of motherboard, I should discuss about five things with you. Don’t fear, I will make them as simple as possible.

1.     Socket

2.     Chipset

3.     RAM slots

4.     PCIe lanes

5.     I/O ports

How to choose a motherboard?

When we buy a PC, our decision should be in the following order.

1.     Choose a Processor

2.     Find the compatible socket for the chosen processor

3.     Choose a chipset based on above socket

4.     Choose a motherboard under your budget having the above chipset

4.     Goes on….

Socket

Socket is nothing but a slot below processor, in which processor sits, on a motherboard. Then what’s special about it?

Each series of processor has different socket types. So we cannot place any processor in any motherboard.

For example:

If you want to buy Intel Core i3 third generation processor, then you should find a motherboard based on LGA 1155 socket, because this processor won’t even sit on Intel’s own motherboard with older sockets.

Suppose if you want to buy AMD Trinity APU, then you should choose FM2 socket. After that you have 3 option A55 or A75 or A85X chipset. If you want more expansion room go for A75 chipset, which has more features than A55, but a bit costly.

Finding a cheap motherboard with A75 chipset is not possible, so if you’re under a tight budget, choose A55 Chipset based motherboard.

Chipset

Chipset can be considered as a manager of motherboard and processor. It’s a chip on motherboard designed by processor manufacturers like Intel and AMD for their corresponding processors.

A chipset had a north bridge and south bridge in olden days. But now the north bridge has been moved inside the processor for better performance.

What does the North Bridge do?

First let me ask you one thing, what does a bridge do? It connects two places which are separated by a long distance or water. The same thing is done by North Bridge too. It connects RAM and PCIe (PCI Express) slots with the processor. Generally it takes care of components, which require very fast communication.

Then What does South Bridge do?

It does the same as North Bridge but there is a small difference, it connects low speed terminals like USB, HDD (Hard disk drive) etc. to North Bridge.

Before going into next section I wish to give you an example,

Assume:-

1.     Processor as Owner

2.     North bridge as GM (General Manager)

3.     South Bridge as Manager

4.     USB, HDD as workers

Workers cannot talk to owner directly; they can talk only up to General Manager that too through Manager only. Only General Manager can talk to owner.

So USB etc. communicates to North Bridge through South Bridge, whereas RAM, Graphic cards etc. communicate to processor through North Bridge.

RAM slots

In olden North Bridge, there was only one lane that connected processor and RAM. So there was no difference between single 4 GB RAM or two 2 GB RAM connected in a motherboard.

Are you confused?

Assume processor is in Chennai and RAM is in Mumbai.

Case 1: Imagine there is only one rail track that is available between both the cities and only train can travel in a track at a time.

So if we have one goods train with 4 carriages or two goods trains with 2 carriages, it makes no difference, because we can send the train one by one only.

But nowadays, after the North Bridge has been placed inside the processor, more lanes are introduced. Today AMD processors have 2 lanes and Intel Ivy Bridge professors have 3 lanes.

So instead of buying a single 4 GB RAM, if you insert two 2 GB RAM, it will be faster. We will see more about RAM and RAM slots later.

PCIe lanes

PCIe is nothing but PCI express. These are slots which hold graphic cards and high end sound cards. They are connected by North Bridge to the processor.

Budget motherboards normally have 1 PCIe slot, but it’s always better to buy a motherboard with at least 2 PCIe slots. We will see more about this in graphic cards section.

I/O Ports

This is nothing but the ports available at the back side of the cabinet. Actually it’s a part of motherboard. We usually connect our speaker, printers, keyboard and mouse etc. to these I/O ports.