Help...strange Boot Up Problem !!!!

My Specs : -

Intel Pentium D 2.66 Ghz

Asus P5n-mx Motherboard

1 X Transcend 2 Gb Ddr2 667 Ram

Mercury 8600gt 256 Mb Gddr3 Graphics Card

Samsung 160 Gb Sata Ii Hard Disk
Sony 20x Ata/ide Dvd Writer

Iball 400 Watt Psu

Intex 600 Va Ups

Recently I Replaced My Old Motherboard Asus P5gz-mx With Asus P5n-mx. Everything Worked Fine For Two Days When Suddenly After Pressing The Power Button, Computer Did Not Boot And In Turn Turned Off After 2 - 3 Seconds. This Problem Then Occured Randomly, I Mean After Many Tries It Booted Up And Everything Worked Fine. After Coming To Desktop Everything Works Fine And Does Not Shuts Down Or Restart On Its Own. Thinking It Of Bios Problem I Flashed The Bios To The Newest Version Available For The Board From Asus Website. But In Vain The Problem Persisted. I Checked All My Connections, Took Out My Ram And Cleaned It But It Did Not Solve The Problem. So Decided To Take My Psu To Iball Service Centre For Checking It. They Repaired It But Still The Problem Persisted. Then I Decided To Replace It With A New Psu Because It Had Warranty But Still My Pc Does Not Startup At One Try. This Problem Is Very Random. I Have Tried To Connect Directly To Power Supply Without Connecting To The Ups But Still The Problem Continues. I Have Also Noticed That The Time When I Push My Power Button My Processor Fan Responds And Rotates For That 2-3 Seconds Time Span. Now I Am Confused..........don't Know Which Component Of My Pc Is Damaged. Kindly Help Me Out............shall Be Very Grateful To Any Suggestions Or Tips. Thank You.

Well, I think you need to get a 500W PSU for proper power flow and also check if the processor is not dying. What are the temps of your computer. If it is very high then try to apply some termal paste onto the heatsink. Post back and let us know the results.

This is a heatsink issue:

The metal of the heatsink is moving very slightly... most of the time shorting the board, putting power where it shouldn't be, and then on occasion the power goes somewhere useful and it boots. Either change the heatsink, or remount it.

I used to play the bootup game too. And I had to go through 3 different heatsinks for a certain board and then sequentially trashed it.

This is also a rare power/motherboard issue, but its nature is very aimed toward something metal hitting the board on the backside or front. I also recommend removing the motherboard and moving it onto carpet/foam to test shorting from anything but the heatsink.

:thumbsup:

A bad, failing, or inadequate power supply is often the cause of this issue. If the hard disk drive is not getting enough power during the first time the computer starts, it will be unable to spin the hard disk platters fast enough to start the computer. However, if you restart the computer two, three, or more times, because the platters are already spinning, it is able to get the drive up to speed and able to boot off the drive.

If you're encountering this issue after installing new hardware in the computer, it's also possible the power supply in the computer is not supplying adequate power to the computer. In this case, your new hardware is the new motherboard, so this signifies this issue. So it will be better to have at the least a 500+ watt power supply for that motherboard.

first of all thanx everyone for ur suggestions......i have tested a 400W psu of ZEBRONICS and it worked fine. no such problems occured. also before when i had asus p5gz-mx mobo it ran fine but after upgrading to p5n-mx this problem arose. can it be a Cabinet power switch problem....i mean does an old Cabinet(2 years old) not supply adequate power from psu through its power cables to a new mobo????

also to say about hard disk, it never initiates booting of computer bcoz the booting sequence is initiated by the onboard RMA chip of mobo where the BIOS is stored. can it be a problem of onboard RMA chip of mobo????

Hey guys back after a long time. actually I didn't get my problem solved..so decided to replace the P5N-MX motherboard and i got the new one 3 days back. but still the problem is continuing!!!
Ram Checked OK
Hard Disk Checked OK
Graphics Card Checked OK
PSU OK
Only left are Processor and my Cabinet.
Please Help!!

Also i have noticed one thing with my 4-pin ATX 12V Power connector...the one connected near the processor. I removed all my components except processor and then also the problem occured but when i removed that 4-pin connector, the problem didn't occur!! So I checked it for nearly 20-25 times and the problem didn't occur. but as soon as i put it back the problem starts occuring randomly. Also another thing I have noticed that this problem never occurs when I start my computer on back up mode of UPS.

Imply these steps:
- unplug
- remove battery
- shift "clear CMOS jumper"
- PLUG IN POWER (so that green LED on motherboard comes on), but do NOT boot
- after 5 seconds, unplug
- shift jumper back
- plug power back in, boot computer. It will complain the CMOS checksum is bad, and it will restore default CMOS settings. Your computer can now boot, but as soon as you do a hard reboot it will fail again. So therefore
- upon booting, press TAB for BIOS POST (not sure if this is needed). Press ALT+F2, which brings you to the facility for flashing the BIOS.
- load the motherboard CD, which has a file called "P5NMX.bin". Browse to this file, tell it to flash it, and all should be fine again.

Quote:

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Originally Posted by PETERAGASSI

Imply these steps:
- unplug
- remove battery
- shift "clear CMOS jumper"
- PLUG IN POWER (so that green LED on motherboard comes on), but do NOT boot
- after 5 seconds, unplug
- shift jumper back
- plug power back in, boot computer. It will complain the CMOS checksum is bad, and it will restore default CMOS settings. Your computer can now boot, but as soon as you do a hard reboot it will fail again. So therefore
- upon booting, press TAB for BIOS POST (not sure if this is needed). Press ALT+F2, which brings you to the facility for flashing the BIOS.
- load the motherboard CD, which has a file called "P5NMX.bin". Browse to this file, tell it to flash it, and all should be fine again.

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I have already performed those steps and that didn't solve my problem so i replaced my mobo. But still after replacing the problem continues. I have also changed my psu thrice but in vain. Also checked all other components and everything is fine. Now i am doubting if something is sorting out!!