[TokBomoh]

System Spec:-
MoBo : Asus P5B LGA775 intel P965
RAM : 3x Kingston 1GB DDR2
CPU : Intel Pentium D 3.00GHz 4MB L2Cache
HDD : Maxtor 160GB IDE
PSU : Cooler Master Extreme 500W (brand new)
GPU : nVidia GeForce 9400 GT
Other : 1 x Sony Optical Drive
Monitor : Acer LED SL200 (new)
Problem :

Didn't used the set since 2011 February. Changed the PSU and bought new LED monitor one week ago.
When the power button pressed on the case all the LED lights up; CPU fan, GPU fan and PSU fan running, but the monitor keep saying no display.There's no beep sound.

Sent to the tech shop where the PSU and Monitor purchased, tested every single item including the PSU on other system, everything works well. Then upon collection when re-assembled the PC powers up.

Brought to home, tried to power up the PC and it booted with all the normal beep sound. Shut off for approximately 18hrs then tried to power up again. Eventually failed.

This time tried to clear CMOS, opened up every single components and cleaned,reapplied the thermal paste on CPU, additionally opened the 'ASUS' printed metal heatsink at the center of the board as in the picture below and cleaned it + applied thermal paste. Then re-assamble and power up. Voila, it booted with normal beeps.

Restarted several times and everything went well. Shut down for 3 hours and then it gone back to zero, No P.O.S.T.

Any suggestion?

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Gday TokBomoh, .

1 to try.
Disconnect the front panel connectors and briefly short out the power on pins.

[iammykyl]

Gday TokBomoh, .

1 to try.
Disconnect the front panel connectors and briefly short out the power on pins.

[TokBomoh]

Been breadboarding.. without the front panel connectors, tried with old and new PSU..
One thing I observed.. sometimes with the new PSU there's a sound on PSU like the sound of overflow, there's current overflow when i felt with my tip of finger on the pin and HDD..

right after the event there's no POST.

however changed to old PSU..still no p.o.s.t
removed the cmos battery and tried to on..there's POST..
re-attached the battery.. positive.. there's POST..

revert to new PSU..no more overflow current sound..
there's POST..

suggestion pls.. all of these done while breadboarding w/o front panel connectors..

edit:-

shut down with new psu for 1hr with all power source unplugged then tried to boot.. failed..

changed to old psu.. success boot. then shut down for 2hrs.. try to boot but failed.. unplugged one of the extended USB port and cmos battery.. tried to boot.. success..

i am confused here.. is it the instability of the electrical current or the CMOS battery or the USB extension?

Edited by TokBomoh, 25 August 2012 - 10:00 AM.

[phillpower2]

TokBomoh

I note the bread-boarding details that you have provided but please see my canned text below;

Couple of suggestions I can make would be first remove the MB and do a barebones set-up on a piece of cardboard (make sure it is larger than the MB) only connect the PSU, the GFX card, 1 stick of Ram and the keyboard.
IF your MB doesn`t have a power test switch you will then need to short out the 2 power on pins on the MB header to get the PSU to activate, you can use a small flat bladed screwdriver or a paper clip bent into a U shape, this is perfectly safe if you do not touch anything else, the idea is to see if we can get a BIOS screen if you do you can then add one component at a time until you find the problem component, you must power down and remove the power cord from the wall before adding a component, second suggestion try a known working PSU, it is not unknown for new components to be bad, third suggestion try and loan an ordinary PCI graphics card (not pci-e) again to try and get a BIOS screen.
Other things worth checking include, if you used stand offs beneath the MB are they in the correct locations (only where there is a screw hole in the MB) otherwise the MB will short out, check for stray screws or bared wires for the same reason

[iammykyl]

If you still connot find the problem.



Remove ever thing except the CPU, perform repeated power on. You should get beep for no memory, every time. if not, test the beeper.
If the beep is consistent. Try the following, Thanks to Phillpower2

How to physically test your Ram.

The following checks require the computer case to be opened so take the following safety precautions 1st, disconnect the power cord from the wall socket and take anti static precautions before touching anything inside, you can do this by touching a bare metal part of the case.

Have a pencil and notepad to hand.

Remove each stick of Ram and blow out the memory slots.

Insert the first stick of Ram in memory slot one, reconnect the power and in the case of a desktop computer the video to screen cable.

Power up the computer and see how it goes.

Make a note of the results.

Repeat the procedure until the first stick of Ram has been tested in each memory slot and the results written down.

Remove the first stick of Ram and put it to one side on top of a piece of paper with the number one on it for identification purposes.

Repeat the procedure with all Ram until each stick has been tested in all slots, the results written down and the sticks identified numerically.

Let s know the results.

Edited by iammykyl, 25 August 2012 - 05:06 PM.

[TokBomoh]

Thanks for your guidance.

I have been testing every single item wile breadboarding / barebones set up.
Turns out everything is normal / working.
For the past 24 hrs I have been trying with my OLD PSU without the CMOS Battery and extended on board USB PORT.
Shut Down with all the power source cables unplugged then reboot turns out well.

I am planning to test the machine with NEW PSU for the next 24hrs with exactly same setup, everything is connected except for CMOS Battery and extended on board USB PORT.

p/s: is overflowing electrical current can cause no p.o.s.t?

edit:

the left one is the part I mentioned as extended on board USB port

Edited by TokBomoh, 26 August 2012 - 04:27 AM.

[phillpower2]

Hi TokBomoh

You must have the CMOS battery in place as this is what powers the BIOS chip which in turn stores the BIOS data which includes your boot sequence and the correct time and date etc.

p/s: is overflowing electrical current can cause no p.o.s.t?

Not quite sure what you mean by this, can you please clarify.

[iammykyl]

Info, CMOS & BIOS. > http://philipstorr.i.../book5/cmos.htm

The computer may, or may not boot, as you have discovered.

The BIOS settings may have changed and are no longer optimal for the hardware.

If you are not sure about the state of the CMOS battery, I would install a new one.
Power on, enter BIOS, set the time and date, set BIOS to factory defaults, save and exit. If successful,

Although your RAM worked in another computer, it could still be defective also a RAM slot may have problems. To test the slots, perform the steps in post
#5.

[TokBomoh]

Hi TokBomoh

You must have the CMOS battery in place as this is what powers the BIOS chip which in turn stores the BIOS data which includes your boot sequence and the correct time and date etc.

p/s: is overflowing electrical current can cause no p.o.s.t?

Not quite sure what you mean by this, can you please clarify.

I understand the feature of the CMOS and BIOS. I am suspecting that the battery could have prevented the boot up process. From what I see the CMOS default date is 01/01/2002 in which i'm expecting 10years of battery half-life has been ended now in 2012.

I can feel overflowing electrical current on the board with the new PSU as in getting the electrical shock when i touch any metal part on the board. But not with old PSU.

Info, CMOS & BIOS. > http://philipstorr.i.../book5/cmos.htm

The computer may, or may not boot, as you have discovered.

The BIOS settings may have changed and are no longer optimal for the hardware.

If you are not sure about the state of the CMOS battery, I would install a new one.
Power on, enter BIOS, set the time and date, set BIOS to factory defaults, save and exit. If successful,

Although your RAM worked in another computer, it could still be defective also a RAM slot may have problems. To test the slots, perform the steps in post
#5.

Can you tell me more on working defective RAM? Because the system detects all the ram even after I manipulated the slots.
I tried every each of the three RAMs in Slot 1. every ram detected.
I put all the ram in Slot 1,2,3. all ram detected.
I put all ram in Slot 1,3,4. all ram detected.
I manipulated RAM positions in the slots. It detected in BIOS and OS.

the problem is always when i shut down for at least 1 hour then try to boot up will give me no post with CMOS battery on.i have to clear CMOS to make it post.

[phillpower2]

From what I see the CMOS default date is 01/01/2002 in which i'm expecting 10years of battery half-life has been ended now in 2012.

As suggested by colleague iammyky replace the CMOS battery, they cost a couple of $, as the BIOS chip is not getting any power it is not storing any settings and so does not know where or what device to boot from.

I can feel overflowing electrical current on the board with the new PSU as in getting the electrical shock when i touch any metal part on the board. But not with old PSU.

Swap the PSUs back and never touch any internal part of the computer while it is connected to the wall socket - whether the power is turned on or not.

[iammykyl]

Can you tell me more on working defective RAM?

Testing the RAM in all the slots was to rule out a possible fault. your results indicate that the slots are OK and the RAM,(not under stress) is detected, When the computer is up and running, I would still test the memory using Memtest86+ > http://www.memtest.org/

[nasiraod]

I am just throwing this out there, your case might not be well grounded, this can sometimes cause the motherboard to behave erratically.

[phillpower2]

I am just throwing this out there, your case might not be well grounded, this can sometimes cause the motherboard to behave erratically.

This is of course correct and thank you nasiraod
This also includes that the correct I/O plate is used and fitted at the rear of the case as this also grounds your MB.

Fitting a new CMOS battery should still be done first before refitting the MB back into the case as this will allow for complete testing of all hardware to be done.

[iammykyl]

nasiraod



Well spotted,

[TokBomoh]

I am just throwing this out there, your case might not be well grounded, this can sometimes cause the motherboard to behave erratically.

FYI the boards and all the parts are on the table.. not in the case while i'm doing all these tests.

Latest Edit :-

Shut down the set for nearly 24hrs with new PSU and unplugged from wall socket. Plugged in and rebooted without the CMOS battery and On Board USB Port Extension, resulting in positive POST. New PSU doesn't release any electrical overflow activity sound, no electrostatic discharge found on other metal part of the board.

I am suspecting unstable wall socket power source that causing No POST. Yet wondering why there's No POST at other wall socket like at the computer shop for instance.

However I'm waiting to buy new CMOS Battery tomorrow.

Update:
Installed new CMOS Battery. Positive P.O.S.T

After all the tests and procedures,my suspicion comes down to unstable electrical source. Pls advice.Thanks.

Edited by TokBomoh, 28 August 2012 - 01:40 PM.