Desktop receiving power but not turning on

[WinSpecToR]

My desktop is receiving power as indicated by the led on the mobo, when I plug in the power, the cpu fan turns on for a second, the fan spins for a few minutes and then it stops. If I leave it on, the psu will power on for a second, power off and cycle while powering the cpu fan again. I'm suspecting the psu. I had a similar problem last time and it turned out to be the cpu but it seems suspicious that this computer is going through 2 psu's?

[redwudz]

Probably first thing, I would unplug all drives, all cards from the PS and see if the same problem occurs. That's to eliminate a few possibilities as in a shorted drive or board.

If the same, then I would probably substitute the PS.

If that doesn't do it, then make sure the CPU cooler is making full contact with the CPU. A loose cooler could also cause the same problem.

You didn't mention if you got any 'beep codes' from the PC. Those can sometimes give you good clues.

If you indeed went through two PS's, then you have some other problems. If the PS's were name brand and sufficient for your PC load, then you may still have a MB or other problem.

[WinSpecToR]

Sorry forgot to mention that I did disconnect all the drives with nothing but the mobo and I'm not getting any beeps. Seems to me it could the board but the troubling thing is that the power button isn't responding. I tried connecting the 2pin wire to a different slot (would this work in theory?) to say the reset button slot. If the power button is glitched then I can't turn it on to test for beeps.

On a side note, I plugged the power in once and my psu and fans came on like they usually do but it made some beeps so I quickly turned that off. The PSU however, has lights built in and they weren't as illuminated as they usually are.

Also noticed a typo, last time I switched the PSU and it solved the problem and wasn't the CPU as I had previously mentioned.

[johns0]

Another problem can be faulty ram,if you have more than one stick installed remove all but one and swap with another ram if it still won't boot up.

[WinSpecToR]

johns0. I took out all ram, drives and video card.

My PSU's were OCZ and the one that currently isn't working is Rosewell.

[johns0]

So did the ocz work and your system booted up ok?

[WinSpecToR]

The OCZ was the first one that failed on me a year or 2 ago and I switched to the Rosewell.

[jagabo]

The PSU is most likely the problem.

[aedipuss]

the system won't boot with no ram or video card. it needs a keyboard also. swapping the power switch wires won't work. you can remove it and start the system by shorting the 2 pins for a second. on switches are just momentary connections.

[WinSpecToR]

the system won't boot with no ram or video card. it needs a keyboard also. swapping the power switch wires won't work. you can remove it and start the system by shorting the 2 pins for a second. on switches are just momentary connections.

The mobo has onbaord video so shouldn't it boot with that? When I say no boot I mean the power isn't coming on at all when I press the power so I dont' think the keyboard will help in this case right?

I just want to know if my comp was working properly and I switch the power cable from the POWER SW slot to the RESET SW slot, would the would the comp turn on when I press the Power Button or Reset button?

Also how do I go about shorting the pins?

TUrns out the PSU is fine as I tasted it on a working comp and it turned on fine.

[redwudz]

The Reset and PWR switches are the same, momentary type. I have switched the Reset switch leads to the PC PWR terminals before to test the PWR switch. You can also short the PWR switch terminals together on the front panel connectors to send the PWR on signal to the MB.

The way the PWR on switch works is it connects to ground and that sends a signal through the motherboard and actuates a switching transistor to connect pin 14 of the ATX PS connector to ground. (Usually pin 13 or 15) This turns on the power supply. You can also hook pin 14 of the ATX PS lead directly to ground and the PS will turn on.



A MB will usually start up without RAM or cards, but you should get a lot of beeps and the PS should run. It obviously won't boot as that's a function of the OS.

It sounds like it might be a MB problem. And those aren't really practical to test.

[MOVIEGEEK]

TUrns out the PSU is fine as I tasted it on a working comp and it turned on fine.

If the PSU is fine then it sounds like the mobo is fried.

BTW: how did the PSU taste..is it like chicken?

[aedipuss]

you need to keep cpu, cpu hsf, ram, the video source the current bios will sent to, and a keyboard connected. a keyboard connected to the ps2 port is best in troublesome cases, not usb.

[WinSpecToR]

@aedipuss If the mobo is working, it should still be able to be turned on and beep without those components should it not?

@moviegeek.. tasted great haha

@redwudz, are you saying I can connect the POWER SW 2 pin leads to those 2 red connectors to short it and try to turn it on that way?

[Nelson37]

Almost all mobo will respond with beep codes with no RAM or Video card present. This in fact a good test for a defective board. Don't think I have EVER seen one that would not boot with no keyboard attached, definitely not for the last decade or so.

Take the board completely out of the case and set on a non-conductive surface. Contact with the metal case and the underneath side could cause a similar problem. Disconnect all cables other than power. Shorted drive or switch cable can cause similar issue. Use a jumper from an old drive or a small screwdriver to momentarily short the PS switch pins.

Did you ever test the original "bad" power supply on another PC?

EDIT: Verify that you have a functioning speaker attached.

Also, you can use the Power switch leads from the case on the Power switch pins on the motherboard, or you can use the Reset switch leads from the case on the Power switch pins on the motherboard, or you can use a jumper on the power switch pins on the motherboard, or you can use a small screwdriver on the power switch pins on the motherboard.

[jagabo]

Don't think I have EVER seen one that would not boot with no keyboard attached

I liked the ones that said "Keyboard error. Press F1 to continue."

[Nelson37]

Yea, those were a riot.

[WinSpecToR]

Almost all mobo will respond with beep codes with no RAM or Video card present. This in fact a good test for a defective board. Don't think I have EVER seen one that would not boot with no keyboard attached, definitely not for the last decade or so.

Take the board completely out of the case and set on a non-conductive surface. Contact with the metal case and the underneath side could cause a similar problem. Disconnect all cables other than power. Shorted drive or switch cable can cause similar issue. Use a jumper from an old drive or a small screwdriver to momentarily short the PS switch pins.

Did you ever test the original "bad" power supply on another PC?

EDIT: Verify that you have a functioning speaker attached.

Also, you can use the Power switch leads from the case on the Power switch pins on the motherboard, or you can use the Reset switch leads from the case on the Power switch pins on the motherboard, or you can use a jumper on the power switch pins on the motherboard, or you can use a small screwdriver on the power switch pins on the motherboard.

I checked the original PSU on another PC and it is still bad while this Rosewill one powered on fine.

"Also, you can use the Power switch leads from the case on the Power switch pins on the motherboard" < What you are suggesting here, is this not the original way every comp is set up? With the power switch lead connected to the power switch pin? Or am I missing something.

As far as the jumper option goes, am I suppose to just put a jumper on the power switch pin, flip the switch on the back of the psu and it is suppose to turn on?

With the screw driver option, is the power to the psu suppose to already be on, and I put the screw driver between the 2 power switch pins to complete the circuit?

Appreciate your clarification.

[jagabo]

With the screw driver option, is the power to the psu suppose to already be on, and I put the screw driver between the 2 power switch pins to complete the circuit?

Yes, PSU switched on, then touch the two pins for a short period of time. Be careful not to short anything else.

[Nelson37]

Or with the jumper, put it on and remove it, that's the "momentarily" part.

Yes, usually the Power switch leads are used. If everything worked OK, there would be no need to investigate possible alternate methods.

EDIT: Important to verify that a working speaker exists. This is related to the beep codes that should be happening. If present, verify beep codes, or lack thereof, then disconnect.

[turk690]

My desktop is receiving power as indicated by the led on the mobo, when I plug in the power, the cpu fan turns on for a second, the fan spins for a few minutes and then it stops. If I leave it on, the psu will power on for a second, power off and cycle while powering the cpu fan again. I'm suspecting the psu. I had a similar problem last time and it turned out to be the cpu but it seems suspicious that this computer is going through 2 psu's?

Something in between the PSU & mainboard is overheating and/or a bigger load than the PSU can accept is being presented to it. You didn't say how much total power the PSUs mentioned is capable of putting out. With those computer specs I'm not going to use anything less than a 700W PSU, higher if my money lets me.
Using a PSU at or near its rated output constantly will make it die sooner. It will be hot, and the first things that will give up the ghost in it are the electrolytic capacitors. These capacitors also abound on the mainboard and can die as well, obviously (bulging top, leaking electrolyte) or otherwise (near-short and dead as a doornail but looking perfectly fine).
When they do, they exhibit the very things observed: PSU turns on and off a few seconds, minutes, or even hours each time; refusing to power on at all (especially if the +5VSB purple line is zero); voltages dangerously low or high (+3.3V dipping down to less than +3V when CPU activity reaches 100%); PSU fan at or near full speed most of the time konks it out and makes the PSU overheat so much it's impossible to turn it on or for more than a few seconds each time; and more.
Dying or dead electrolytic capacitors compound the problem because they are now near-shorts and so instead of functioning as filter or bypass as intended, they now present a (possibly considerable) load in addition to the mainboard & other peripherals.

[WinSpecToR]

Or with the jumper, put it on and remove it, that's the "momentarily" part.

Yes, usually the Power switch leads are used. If everything worked OK, there would be no need to investigate possible alternate methods.

EDIT: Important to verify that a working speaker exists. This is related to the beep codes that should be happening. If present, verify beep codes, or lack thereof, then disconnect.

I'm pretty sure the mobo speakers are working as I do recall hearing one quick "siren", which according to my mobo maual is a processor over heat, I turned the comp off as soon as I heard it so it should have not done any damage. Also, I don't see how this is possible since I did not touch the processor or it's fan.

And for the momentary part, so I'm suppose to put it on and remove it while the power is on right to confirm? I tried it last night with the jumper on and nothing happened, guess why that didn't work.

My desktop is receiving power as indicated by the led on the mobo, when I plug in the power, the cpu fan turns on for a second, the fan spins for a few minutes and then it stops. If I leave it on, the psu will power on for a second, power off and cycle while powering the cpu fan again. I'm suspecting the psu. I had a similar problem last time and it turned out to be the cpu but it seems suspicious that this computer is going through 2 psu's?

Something in between the PSU & mainboard is overheating and/or a bigger load than the PSU can accept is being presented to it. You didn't say how much total power the PSUs mentioned is capable of putting out. With those computer specs I'm not going to use anything less than a 700W PSU, higher if my money lets me.
Using a PSU at or near its rated output constantly will make it die sooner. It will be hot, and the first things that will give up the ghost in it are the electrolytic capacitors. These capacitors also abound on the mainboard and can die as well, obviously (bulging top, leaking electrolyte) or otherwise (near-short and dead as a doornail but looking perfectly fine).
When they do, they exhibit the very things observed: PSU turns on and off a few seconds, minutes, or even hours each time; refusing to power on at all (especially if the +5VSB purple line is zero); voltages dangerously low or high (+3.3V dipping down to less than +3V when CPU activity reaches 100%); PSU fan at or near full speed most of the time konks it out and makes the PSU overheat so much it's impossible to turn it on or for more than a few seconds each time; and more.
Dying or dead electrolytic capacitors compound the problem because they are now near-shorts and so instead of functioning as filter or bypass as intended, they now present a (possibly considerable) load in addition to the mainboard & other peripherals.

I'm currently running 650w. The capacitors look fine but anything is possible I suppose. Like I said I'm just trying it now with the bare bones.

[jagabo]

And for the momentary part, so I'm suppose to put it on and remove it while the power is on right to confirm?

Yes. You are simulating exactly the same thing the power switch does. When you press the switch down you short those two pins together. When you let the switch up you are no longer shorting the pins. Basically, you're using a screwdriver as your conductor instead of wires and a switch.

[Nelson37]

By "siren", do you mean a continous tone? Not pulsing in some way? This can also indicate a dead short somewhere, could be actual contact issue or bad components as mentioned.

At what point in this sad saga did this sound occur, while it still worked? Did it work again after this? Ever heard a beep after this?

[WinSpecToR]

@jagabo Tried it and it still didn't work, I just can't believe it was working fine, i switched sata cables on one of the drives and now the whole thing doesn't work

@Nelson37 No it really sounded like a siren and not a continous or pulsing tone, even if it were continous or pulsing, I didn't leave it on long enough to get any patterns and now its not giving me any beeps or sirens. The siren occured after it stopped working and its been dead since but like I mentioned. When I plug the power in, the fans still spin for a bit then stop with no reaction to the power button.

[Nelson37]

Trying to get the sequence of events, here. It WAS working, THEN it ceased to boot but did indicate power as in fans running. AFTER THAT, it gave the "siren", and has not beeped since?

I am confused as above you specifically mention, apparently sometime AFTER the initial failure to boot, that it did start to power up once and gave some beeps. The pattern of those would be exceptionally important as it would indicate that the board is not "brain dead".

If this "siren" had a distinct "buzz" to it, different than the normal, somewhat musical beep tone, in my experience that is NOT a processor overheat warning but an indicator of severe problem, shorted contact, serious power problem, or bad component.

If you got a normal beep code AFTER the siren, that means the problem was temporary and for some reason went away. If there was NEVER a normal beep code AFTER the siren, what you heard may have been the death scream of the mobo.

Same advice as before. Separate the board from all possible external short possibilities, ALL cables, including switches, removed, board out of case on non-conductive surface, check the underside of the board carefully, check the whole board carefully for loose screw, paper clip, anything metal. Attach power only, including the necessary 4-pin black and yellow cable. Test with no RAM, then add one stick. Test also with KNOWN GOOD power supply. If the KNOWN GOOD factor involves the current PSU that will boot another PC, that "other PC" needs to have similar power requirements and IDENTICAL power connections. I would prefer a brand new PSU.

If no results, then dead board or possibly CPU. Bad CPU far less likely, but cannot be eliminated without either another CPU or another board, compatible to the current ones. However, bad board can kill a CPU, bad CPU can kill a board, so this testing step is usually not cost effective unless you have such parts available and they are disposable.

[jagabo]

If this "siren" had a distinct "buzz" to it, different than the normal, somewhat musical beep tone, in my experience that is NOT a processor overheat warning but an indicator of severe problem, shorted contact, serious power problem, or bad component.

Yes. I've heard that from components with a power to ground short, in the process of frying.

[Nelson37]

Been trying to think of how to describe that sound, different from the normal beep.

Harsh, strident, less musical, different tone or musical note, louder? I think of it as an unpleasant sound, but that's probably because I know it means bad things.

I have had systems do this and completely recover, in the case of short against the PC case or a loose screw or some such. However, when they do that, and there is no foreign object, and no beep codes afterward, that's all she wrote.

[WinSpecToR]

@nelson37 This "siren" I only heard momentarily as I figured something was wrong so I turned the power off pretty much immediately. The siren and spinning of fans came on when I flipped the switch on the PSU and not from the power button or shorting the 2 pins, which did not work.



Just to confirm, you guys wanted me to short the shown in diagram E pin 6 and 8 correct? Or were you guys talking about the ones in Redwudz's pic? In any event I tried to put a jumper on pin 6 and 8 and that didn't work after removing it momentarily in getting the power on. I also tried the screw driver approach and that didn't work either. The sequence of event was: Was working > Stopped working > Fans and PSU came on after flipping the switch and siren came > Power led on mobo, cpu fan still functional but unable to turn on power by any means.

As for the siren noise, think of it as the one you hear in old World War movies.

[WinSpecToR]

Visually, the board looks ok.