My desktop has refused to come on, I Changed the hard disk and it worked for a while until it stopped again.
Ive tried checking every components but i dont seem to find the problem.
All i here wen i put it on is a alarm sound from the mother board itself.
Pls i need ur opinions.
Thx

Your computer is trying to tell you something,
Listen to the amount of beeps you are hearing as you power your system,
From that you will know the problem,

Beep Code Descriptions
1 short DRAM refresh failure
2 short Parity circuit failure
3 short Base 64K RAM failure
4 short System timer failure
5 short Process failure
6 short Keyboard controller Gate A20 error
7 short Virtual mode exception error
8 short Display memory Read/Write test failure
9 short ROM BIOS checksum failure
10 short CMOS shutdown Read/Write error
11 short Cache Memory error
1 long, 3 short Conventional/Extended memory failure
1 long, 8 short Display/Retrace test failed

More,

Beep Code Description
No Beeps No Power, Loose Card, or Short.
1 Short Beep Normal POST, computer is ok.
2 Short Beep POST error, review screen for error code.
Continuous Beep No Power, Loose Card, or Short.
Repeating Short Beep No Power, Loose Card, or Short.
One Long and one Short Beep Motherboard issue.
One Long and Two Short Beeps Video (Mono/CGA Display Circuitry) issue.
One Long and Three Short Beeps. Video (EGA) Display Circuitry.
Three Long Beeps Keyboard / Keyboard card error.
One Beep, Blank or Incorrect Display Video Display Circuitry.

Hope this helps