MB's, GB's, TB's.. But, how many??

Storage drives are getting significantly cheaper. So cheaper, in fact that people have started buying 1 TB hard drive instead of a 750 GB one. Cheap storage space is not everything. You have to consider the speed of the system as well.
While buying an internal hard drive, people often forget that a larger hard drive means a slower system. And also, more number of hard drives mean a slower system as well.
And if disaster strikes and your hard drive crashes, you lose more amount of data than you would have, had you would have had a smaller one.

Research says that as the years have progressed, hard drives have become cheaper while their reliability has plummeted considerably, especially for larger capacity hard drives.
In daily life too, you'll see 500 GB and 1 TB ones crashing more frequently than their corresponding 320 or 750 GB ones.
So the question arises, how do we choose a good HDD with ample space. Well that's extremely simple, keeping a few points in mind.
When calculating storage space requirement, do not keep more than 35 GB reserved for your system partition containing your operating system and your basic everyday applications. Add in an appropriate size for your productivity apps like adobe suites, autodesk products, etc etc.
After that do not start counting your pictures, documents, music and videos. Remember that you can save your pictures and videos to an external hard drive or the cloud for more reliable and efficient storage. Just keep the important ones on the system itself. Plus add a couple of 100 GB if you are a gamer.
But that's it, no one needs more storage than that, and there is no need to install a hard drive that's gigantic.

Compatibility of RAM with the system

The second most important thing everyone needs to keep in mind is whether the RAM he/she is going to buy will actually work with the system or will it get burned as soon as it is installed. You can be sure of the compatibility of RAM with the system by a very simple test. Just locate your motherboard manual (printed or online) and see what type and speed of RAM's are safe to use with the motherboard.
The motherboard documentation will usually include the following types of specifications:

• Memory Type: DDR3 1600/1333 MHz
• This means you can ONLY use a RAM of the type DDR3.
• This also implies that you will be safe to use RAM's with the speed of either 1600 or 1333 MHz. The rest of them might not work or might get burned in due course.

• Max Memory Size: 32 GB
• This specification specifies the maximum amount of memory you can install in your system without causing any harm to it.
• You are safe to use lesser amount of RAM than specified if you want or if you are on a tight budget, but make sure you do not exceed this limit.

You should also calculate the maximum RAM supported per slot by the motherboard by dividing the Max Memory Size by the number of sockets present on the motherboard.
For example, in a system with four RAM slots, you can install an 8 GB chip in each slot for a 32 GB motherboard.
However, in a system with eight slots, you can install 4 GB chips in each slot for a 32 GB motherboard. Using a chip with a higher memory size like 8 GB ones in this case will not be beneficial for your system.

Specifications of an Optical Drive

Various types of optical drives are available in the market. These include CD readers, CD writers, DVD readers, DVD writers, DVD combos, BD readers, BD writers and BD combos.

The specifications of an Optical Drive drives to be considered are:

Supported Media Types: The optical drive must support a major part of available types of discs in the market. Examples are CD-ROM ,

DVD-R ,DVD-ROM ,CD-RW ,CD-R ,DVD-RAM ,DVD-RW ,DVD+R and DVD+RW. Note that CD drives do not support DVD's or BD's and DVD drives do not support BD's. Also, the supported media types are different for a drive's read and write capabilities.

Interface: The interface that an optical drive uses and the port that it will use to connect to the system. The interfaces have transfer speeds of their own. For example, a max. of 167 MBps for IDE, 600 MBps for SATA. But, the current technologies available for optical drives can only provide speeds that are lower than modern systems. So in case, both the ports are available in your system, the interface is not much of a specification.

Buffer Size: The optical drive buffer works in exactly the same manner as the cache of a hard drive It stores a fraction of frequently accessed data that can be accessed extremely fast. It helps the system to access data from the drive even if the processor is being utilized 100% by other processes for a fraction of a second. Usually 1 or 2 or 4 MB.

Read & Write Speeds: All optical drives have different read and write speeds and different read or write speeds for different types of media. For example, DVD drives have a speed of 16x, 20x, 24x (where x is 1.35 MBps) and CD drives have a speed of 32x, 48x, 52x (where x is 150 KBps). An optical drive will always write different types of media at different speeds (For example, a CD at 48x, a DVD at 16x and a re-writable DVD at 4x). 

Specifications of a Hard Disk

Hard Disks have a few performance specifications that a buyer must always know accurately before purchasing the hard disk. Better specs will obviously make the system perform faster. The specifications are:

• Capacity: The amount of data that the disk can store. Usually 100's of GB's or TB's.
• Cache: A small memory chip that stores a fraction of frequently accessed data that can be accessed extremely fast. Usually 8 or 16 or 32 or 64 MB.
• Spin Speed: The speed at which the hard disk platter rotates. Usually, 5400 or 7200 or 10000 rpm.
• Average Seek Time: The average time in which the R/W head can be positioned over the requested track for random read/write requests. Usually, ~8-10 ms.
• Average Latency: The average time for the disk to rotate the platter and position the correct sector under the R/W head. Usually, ~3-5 ms.
• Interface: The interface that the hard disk uses and the port that it will use to connect to the system. The interfaces also have transfer speeds of their own. For example, a max. of 167 MBps for IDE, 600 MBps for SATA.

Ports for storage devices

Computer systems have a variety of secondary storage devices, some essential and the others optional. Some of these include hard-disk drives, optical drives, tape drives, floppy drives, etc.

For the transfer of data to and fro from the devices controllers are required to control the ports for connecting the devices. For the ports already present in the motherboard, usually the controller is on-board the motherboard too. The ports for hard-disk drives and optical drives include:

Parallel ATA (PATA/IDE):

• 40 pin cable and port
• max cable length: 45cm
• max number of hard drives: 4 (only in some motherboards, 2 per cable)
• max transfer speed: 133 MB/s

Serial ATA (SATA):

• 7 pin cable and port
• max cable length: 1m
• max number of hard drives: 8 (till now, one per cable)
• max transfer speed: 150-600 MB/s

SATA ports are fast replacing PATA ports. Controllers for extra ports like additional SATA or PATA ports, SCSI, USB, etc. that have been added via PCI card or similar are built on the PCI card itself.

There are ports for additional storage expansion as well like USB and SCSI. SCSI is mainly used with servers that have large arrays of hard-disk drives whereas USB controller is already present on the motherboard. The latest USB 3.0 specification is supposed to achieve 600 MB/s.