[nizzor]

past few weeks my computer has been uncooperative with me. there were times where it wouldn't turn on, then i'd have to restart everything (turn off all power bars to disable routers, modems, etc) for it to work again. i can't remember when or how this problem started since my computer has been always fine. i've had it for over a year now.

so i've been patient with the steps i have to go through in order to get my computer to turn on and stay on. but now a new problem submerged - it won't turn on at all. actually there are cases when i see it turn on but for a split second. I see the indicator light on the front of my tower flash for a split second and it dies. i can hear the fans start up for a split second then die. my PSU is fine i think, i see the mobo light on (so power is going through) but What the...? it's a 400w PSU so i dont think i should have problems. I just disconnected rear fan in case not enough power is going through the system but that didnt help. my comp's been dead for about 3 days now and i'm starting to get annoyed. any help?

specs:
Intel P4 3.0 GHz
2x512 DDR Ram
ASUS P4P-800
ATI Radeon 9600 XT
400W PSU

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Have you tried testing your memory or tried a new power supply?

For memory- run memtest86

[Hemal]

Have you tried testing your memory or tried a new power supply?

For memory- run memtest86

[Samm]

Could be any number of things I'm afraid, so lets eliminate them bit at a time.
First, can you disconnect any peripherals (printer/scanner/USB devices) leaving just the monitor & keyboard. Disconnect mouse only if its USB.

Remove all PCI cards.
Unplug all drive cabling at the motherboard, incl FDD, CD, HDD
Disconnect all molex connectors from drives
Clear the CMOS for about 10 secs
Try & boot the system

Let me know what happens

[nizzor]

well i did what you asked all at once - monitor, keyboard, vid card, cpu, ram, and mobo all that remains. the comp still doesnt turn on. doesn't even have that split second sign of life anymore.

stuff removed:
32x cd-rom (i kno been meaning to replace that )
floppy drive
SATA Seagate HDD 120GB
5.1 Sound Card

Edited by niggzor, 07 May 2005 - 07:54 PM.

[Hemal]

try running memtest86 to verify that the ram is good or try putting in new ram- again i will tell you that trying the case with a new power supply could be the answer- that was your original hunch and you know the situation better then we do

[nizzor]

i will consider getting a new power supply, but are there any other comments or suggestions before i buy a power supply? there may be a diff problem i overlooked and might just squander away my money on a new psu

[amin ne]

Power supply is the problem for sure

[Samm]

I agree with Soxrok, it is almost certainly the PSU however I appreciate you don't want to buy replacement parts if they're not needed.
If you don't have a spare PSU to test the system with, then there's only one other thing I can suggest - please follow these instructions carefully or don't try them at all:

1. Disconnect all the internal power connectors in the system, including the mobo atx connectors, drives etc. You can leave one CDROM drive connected to the psu ONLY if you want - this will provide a load - but it's not strictly necessary.

2. Get a bare metal paper clip, straighten it out & then bend it into a tight U shape.

3. Look at the 20pin ATX connector on the PSU - there should be one green wire. Look on the underside of the connector for the corresponding pin - this will be the 4th pin along from one end. When you are sure you have located the correct pin, connect the PSU to the mains & switch it on at the back.

4. Take your paperclip & insert one end up into the green pin & the other end into one of the neighbouring pins fed by a black wire.

5. If the PSU doesn't power up or if it powers up but goes straight off again, then you know it's dead.

6.If the PSU powers up & stays on (leaving the paperclip in place), then it's possibly working. The next stage is to test the outputs with a multimeter but let me if it fires up or not first before we worry about that.

[nizzor]

ugghhh.. well i did it and it turned on and stayed on (i heard the fan working). so now what. :S

[cauli1]

Hi. Yes i agree it's the power supply. Check in Bios how much W's your pc is getting and post it in here.



Regards,
Cauli

[Samm]

Do you know how to use a multimeter because you need to test the voltages on each of the non-black pins on the ATX connector of the PSU?

[nizzor]

i think i've used one before. but, i'm pretty sure i dont own one.

edit: question: cuz i really need that computer, just wondering what testing pins ultimately does. if say, i find a dead pin or something, what will i need to do to fix it? does it involve cutting off that wire or replacing it or something? maybe using different pins to avoid the problem and leave the dead one alone? or will getting a new psu be the easier way out (altho im not really leaning towards this solution )

ps - i really appreciate all the patience and help you are giving Samm.

Edited by nizzor, 09 May 2005 - 06:06 PM.

[Samm]

No, if the voltages readings are incorrect on any of the pins, you need a new PSU, it's not fixable I'm afraid.
What testing the psu does is, it confirms whether the 'powergood' voltage being supplied to the mobo when you switch it on, is correct. If this voltage is absent or below about 1V, then the mobo doesn't power up.

[nizzor]

okay, sorry for the long reply, been quite busy for the past few days. i just bought a multimeter, so what am i supposed to do now?

edit: been looking around for tutorials on how to test on power supplies and find that most of them lean helping digital multimeters.. [bleep] and i bought an analog one. well, i'm still trying to browse more, but any help on what to do from you guys is appreciated

Edited by nizzor, 15 May 2005 - 04:00 PM.

[Samm]

An anolog meter is fine & works the same way. Just make sure you have the correct range selected (ie DC Voltage upto 20V).

What you need to do is :

1. Get the PSU working (completely isolated from the computer still) using the paper clip method

2. Set the multimeter to the DC Voltage range (VDC) upto 20V. (or the closest range above 12V, if the meter doesn't have a 20V scale). Also check that the black probe is connected to the black socket on the meter (usually marked COM) & the red probe is connected to the red socket usually marked with several symbols incl V, mA & the omega (resistance) symbol.

3. Select one of the black wires on the atx connector of the psu & insert the black probe into the corresponding pin on the underside.

Next, insert the red probe into the following pins one at a time, recording the voltage reading for each one :

Test all the red wire pins (these should all register +5V)
Test all the orange wire pins (these should all register +3.3V)
Test the white wire pin (-5V)
Test the blue wire pin (-12V)
Test the yellow wire pin (+12V)
Test the purple pin (+3.3V or +5V is good)

There may be a slight variation for any of the pins (eg 4.95V for a 5V lwire is acceptable). Its also harder to read the results very accurately on a analog meter but a significant difference in voltage (such as 3V on a 5V wire) will be easily noticable.

Let me know what the readings are.