Don't know whats the problem
I turn on my PC (Press ON the CPU power button ,CPU fan is working) and there's no Monitor display and after keeping in that state for a while (about 15 mins or so) and then switching OFF the supply from the main plug and then Pressing the ON button the PC starts ,the Engineer who got this PC assembled for me (Got this new CPU 4 months back ,just using the old Hard-disk which is about 7 months old)pointed out that there might be some problem with the MotherBoard and he took the MB and got it repaired from Gigabyte's Service Center (I assume there was some problem with the MB itself) and then it worked as it should for a day and then this peculiar problem started all over again ,I phoned the engineer and from the looks of thing he says that there might be problem with my Hard disk (which doesnt comes in the warranty period,the parts he got it for me have to be checked for free as they come in the warranty) ,looks like he will charge me a hefty amount unless you guys let me know if it is indeed a hardware problem or something to do with my hard disk?

Thanks!

A bad hard drive will not cause this; your computer is not even reaching the BIOS that is why you are not getting the POST screen.



Your problem is either a bad mainboard or a bad power supply. Of the two, I would guess you have a bummed mainboard.

any warning beeps at startup?

Yeah theres a beep at startup ,Thanks !

single beep, continuous beeps, long, short, combination?

we do need to know the computer specs. motherboard maker and model number, video adapter make and model number, amount and type of ram, hard drive size, bios maker and model number in order to be able to help.

Just a single beep !!

Operating System: Windows XP Professional (5.1, Build 2600) Service Pack 2 (2600.xpsp_sp2_gdr.070227-2254)
Language: English (Regional Setting: English)
System Manufacturer: Gigabyte Technology Co., Ltd.
System Model: GA-VM900M
BIOS: Award Modular BIOS v6.00PG
Processor: Intel® Pentium® Dual CPU E2140 @ 1.60GHz (2 CPUs)
Memory: 960MB RAM (DDR2)

---------------
Display Devices
---------------
Card name: NVIDIA GeForce 8600 GT
Manufacturer: NVIDIA
Chip type: GeForce 8600 GT
DAC type: Integrated RAMDAC
Device Key: Enum\PCI\VEN_10DE&DEV_0402&SUBSYS_228B1682&REV_A1
Display Memory: 256.0 MB
Current Mode: 1024 x 768 (32 bit) (60Hz)
Monitor: Plug and Play Monitor

Hard-Disk
Total Size:160 GB

C:20 GB free
D:12
E:10

Is this enough or should I post something more ,anyways thanks for helping ,Appreciate you guys !

1 short beep probably means memory problem. if there's more than 1 module pull 1 and boot, if that doesn't work try the other module.