> Defective Hard disk:

Following items can indicate a defective harddisk:

- The harddisk makes ticking sounds.

- The harddisk makes a weird tune (serious !).

- The harddisk makes a shrieking or rattling noise.

- The harddisk smells burnt; some parts can even smoke.

- The harddisk is not recognised any more by the bios or windows / OSC / Linux / Etc...

- Windows / OS X / Linux / Etc... cannot boot anymore.

- The computer stops reacting while you are at work.

- Your harddisk suddenly seems to have an incredible capacity (e.g. 0 GB of 10000 GB).

- Your harddisk still appears in the bios but its normal name has changed.


Common symptoms of bad ram:

  There are many indicators of bad memory, but the most common ones are:

• Computer not booting at all, beeping endlessly. When this happens all you can do is replace the RAM by trying another stick. You wont be able to use any ram diagnostic software in this instance.
• Distorted graphics on the screen. However it is possible this can be video card related.
• Blue screens of death during the installation of Windows XP or Windows 2000. This is an obvious sign of faulty RAM.
• Crashes or blue screens during normal operation of the system (emails, web surfing etc.)
• Crashes during memory intensive tasks such as using Photoshop, playing 3d games etc..

The CMOS battery is dead or dying:

      Explanation:
                The system is exhibiting behavior that implies that the CMOS battery is dead. This can include lost CMOS settings, the real-time clock losing time, or of course dead battery warnings at boot time.

      Diagnosis:
                On an older PC, it is normal for the CMOS battery to fail at some point in time. They usually last for many years, with over five years being the norm, at least on older machines. Nobody knows for sure how newer machines will fare. On a new motherboard, this sort of message is a sign of a defect, although you shouldn't worry about it if it appears only the very first time the board is powered up. The solution is replacing the battery, and this can be an either easy or impossible task, depending on how much thought the motherboard manufacturer put into the design.

  A PC (Personal Computer)                            

           is a system, consisting of many components.  *Computer Hardware Installation
Some of those components, like Windows XP, and all         >By pass or remove the BIOS Password
your other programs, are software.                                       > Defective Memory (RAM)
The stuff you can actually see and touch, and would           > Defective Hard disk
 likely break if you threw it out a fifth-story window,           > Defective CMOS Battery
 is hardware.                                                                           >

Not everybody has exactly the same hardware. But 
those of you, who have a desktop system, , probably
have most of the components shown in that same 
figure. Those notebook computers probably have most
 of the same components. Only in this case the
 components are all integrated into a single book-sized
 portable unit.

The system unit 

            Is the actual computer; everything else is
 called a peripheral device. Your computer's system
 unit probably has at least one floppy disk drive,
 but probably in this present generation no more
 hard disk exist so now the CD or DVD drive, into
 which you can insert CD or DVD Tape. There's
 another disk drive, called the hard disk inside 
the system unit. You can't remove that disk, or
 even see it because it will be damaged. But it's
 there. And everything that's currently "in the 
computer" is actually stored on that hard disk. 

The floppy drive and CD drive

          Are often referred to as drives with removable media or removable drives for short, because you can remove whatever disk is currently in the drive, and replace it with another. Your computer's hard disk can store as much information as tens of thousands of floppy disks, so don't worry about 

running out of space on your hard disk any time soon. As a rule, you want to store everything you create or download on your hard disk. Use the floppy disks and CDs to send copies of files through the mail, or to make backup copies of important items.

Random Access Memory (RAM)

            There's too much "stuff" on your computer's hard disk to use it all at the same time. During the average session sitting at the computer, you'll probably use only a small amount of all that's available. The stuff you're working with at any given moment is stored in random access memory (often abbreviated RAM, and often called simply "memory"). The advantage using RAM to store whatever you're working on at the moment is that RAM is very fast. It is faster than any disk. But remember, a memory restored temporarily only.

             So if RAM is so fast, why not put everything in it? Why has a hard disk at all? The answer to that lies in the fact that RAM is volatile. As soon as the computer is shut off, whether intentionally or by an accidental power outage, every thing in RAM disappears, the memory is empty again. Just quickly as a light bulb goes out when the plug is pulled. So you don't want to rely on RAM to hold everything. A disk, on the other hand, holds its information whether the power is on or off.