the pc has no power *was getting occasional power and would run fine for a few restarts, then it would stop powering. it's sporadic. started after a bad t-storm* i've checked all the connections, the power supply, the ram, took out the battery.. i know it could be motherboard or cpu *motherboard had green light on (voltage check/flea power)* is there a tool i can buy to test the mb and cpu? I would rather not buy replacements if its not that. is there something i'm forgetting to check?
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no power to pc, how to check mb and cpu 1
- Thread starter kell3625
- Start date
Power Supply.
If you have another computer with a power supply that will work with that computer, try swapping that out, and see if it fixes the problem. Just b/c it gives a green light doesn't mean the PSU is still good.
If it still doesn't work with a different power supply it's likely the board.
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"If to err is human, then I must be some kind of human!" -Me
If you have another computer with a power supply that will work with that computer, try swapping that out, and see if it fixes the problem. Just b/c it gives a green light doesn't mean the PSU is still good.
If it still doesn't work with a different power supply it's likely the board.
--
"If to err is human, then I must be some kind of human!" -Me
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- #3
goombawaho
MIS
Absolutely correct ^^^^^^ Only trust the power supply tester if it shows the power supply is dead (lights don't light up as they should).
Never trust it if says the power supply is fine. A false positive is possible and I've seen quite a few of them. Easier to have one on hand or borrow one to VERIFY.
Never trust it if says the power supply is fine. A false positive is possible and I've seen quite a few of them. Easier to have one on hand or borrow one to VERIFY.
check the switch too... had a problem with a PC not turning on, took it all to bits and built it out of the case cleaning each peice as i went and i just shorted the pins to turn it on and it was fine... put it back in the case and coldnt turn it on?!? i thought it was a short, maybe through the case somewhere and pulling it out and putting it back checking i gave up attaching the LED's and switches and just shorted the pins whilst it was in the case and it worked! never seen a switch just not work, the problem was with the bit that pluged onto the mobo had lost metal connection inside it seemed ?!?!? i just used the reset switch for power instead!
This used to be much more common, I believe. I've personally seen a bad power switch only once so far. And I did the same thing for the friend of mine who owned the PC. I just routed the reset switch, b/c I knew they wouldn't want to spend money on a new case. Actually, the case was pretty crummy anyway. This switch was broken in the actual mechanisms behind the switch itself, rather than the wire/connection end.
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"If to err is human, then I must be some kind of human!" -Me
goombawaho
MIS
Switches are a somewhat common soure of problems, but often the BUTTON on the front is not part of the switch. It just pushes back and into the actual switch. I've seen where people push the front button too hard and push the actual switch out of it's little cradle and then the front button can't go in far enough any more to actually engage the switch.
A switch is best tested by shorting the jumper on the motherboard that comes from the front panel switch. This, in effect, is the same as pressing the switch button, but it cuts out the middle man and proves the switch to be/not to be the problem.
A switch is best tested by shorting the jumper on the motherboard that comes from the front panel switch. This, in effect, is the same as pressing the switch button, but it cuts out the middle man and proves the switch to be/not to be the problem.
- Thread starter
- #7
thank you, this has all been awesome advice. i am going to buy a psu tester. it might be good to have around in case and it will help in this situation. I can't switch the psu's *which is normally how i test* because i have 20 pin psu's and this is a 24 pin. i will also try the switch idea. i'll post to see if i've resolved it. thanks for all the help. i assumed if the light on the mb lit up then the psu was fine.
Actually, you'd be surprised. Oftentimes, the 20 pin power connections will work just as well for the 24 pin connection boards. I've done it before with no issue, and I've read from various sites online that it's perfectly safe. Just make sure you correctly connect the power.
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"If to err is human, then I must be some kind of human!" -Me
Then there is also the 20 to 24 pin adapter which can be had for very little:
--
"If to err is human, then I must be some kind of human!" -Me
--
"If to err is human, then I must be some kind of human!" -Me
- Thread starter
- #10
goombawaho
MIS
That would be "not a problem". Long explanation, but that function is not necessary.
- Thread starter
- #12
goombawaho
MIS
I'll see if I can dig up the link to a really good web site on power supplies and connectors. It will tell why the -5V is not necessary in case you want to read about that and more.
- Thread starter
- #14
goombawaho
MIS
Here it is - everything you wanted to know about PC power and connectors to make it all work together.
Here's a quote from that page, which is what I was telling you in my post up the page:
"The -5 volt line on pin 18 was made optional in ATX12V 1.3 (introduced in 2003) because -5 had been rarely used for years. Newer motherboards virtually never require -5 volts but many older motherboards do. Most newer power supplies don't provide -5 volts in which case the white wire is missing."
If wire is missing, power supply tester will show it as bad.
Here's a quote from that page, which is what I was telling you in my post up the page:
"The -5 volt line on pin 18 was made optional in ATX12V 1.3 (introduced in 2003) because -5 had been rarely used for years. Newer motherboards virtually never require -5 volts but many older motherboards do. Most newer power supplies don't provide -5 volts in which case the white wire is missing."
If wire is missing, power supply tester will show it as bad.
goombawaho
MIS
No, it's not that simple, actually, DonMc67.
The PSU has to SEND the power, yes, but the Motherboard also has to RECEIVE said power, and be able to do something with it. Then there's also the power switch.
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"If to err is human, then I must be some kind of human!" -Me
The PSU has to SEND the power, yes, but the Motherboard also has to RECEIVE said power, and be able to do something with it. Then there's also the power switch.
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"If to err is human, then I must be some kind of human!" -Me
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