Hi, Came to switch on my PC this morning and it initially started up. Went away came back an the system was off. Tried to restart, fans just spun quickly neon light flashed and then nothing. No beeps nothing. Green LED on system board was on but other than that nothing. Unplugged the power supply for 15 seconds, plugged in and switched on and same again. Is this likely to be a PSU problem or a mobo failure?
Problems with PC Not Starting
- Thread starter GodMac
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Is the PSU fan spinning?
If not, do a quick PSU test :
"Hotwire" Test
The test here is to start up the PSU without the motherboard or power switch so that power is distributed along the rails as soon as the PSU is switched on. By attaching a known working fan to one of the Molex connectors we can soon tell if the PSU is working or it's a problem with the motherboard. Here's how:
- Firstly, make sure the PSU is switched off and mains disconnected.
- Disconnect all power leads to all devices including the motherboard ATX connectors.
- Now take a small piece of old cable and strip the ends.
- Take the 20/24pin ATX connector and look for the pin the has a green cable going. There's only one.
- Place one end of the cable into the green pin and the other end into any black pin, as shown below. Make sure they are securely in place.
- Attach a known working fan to one of the Molex connectors
- Plug the PSU back in and switch on. The PSU should start and the fan should start spinning immediately.
If the fan doesn't spin then it would appear to be a faulty PSU. If it does work however, then it could be a faulty motherboard
If not, do a quick PSU test :
"Hotwire" Test
The test here is to start up the PSU without the motherboard or power switch so that power is distributed along the rails as soon as the PSU is switched on. By attaching a known working fan to one of the Molex connectors we can soon tell if the PSU is working or it's a problem with the motherboard. Here's how:
- Firstly, make sure the PSU is switched off and mains disconnected.
- Disconnect all power leads to all devices including the motherboard ATX connectors.
- Now take a small piece of old cable and strip the ends.
- Take the 20/24pin ATX connector and look for the pin the has a green cable going. There's only one.
- Place one end of the cable into the green pin and the other end into any black pin, as shown below. Make sure they are securely in place.
- Attach a known working fan to one of the Molex connectors
- Plug the PSU back in and switch on. The PSU should start and the fan should start spinning immediately.
If the fan doesn't spin then it would appear to be a faulty PSU. If it does work however, then it could be a faulty motherboard
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Hi, this is what I've done so far:
1, Unplugged the memory and rotated individual pairs as I have 1gb modules and all 4 can't have gone. Still not starting.
2, Unplugged all main devices including power to Gfx card and still no joy.
The only option now is to take my PSU out of my other system and connect that. This isn't going to be a 5 minute job, so before I do this can anyone tell me if the PSU is at fault, why would the mobo LED be on and what could be causing this if it is the PSU?
1, Unplugged the memory and rotated individual pairs as I have 1gb modules and all 4 can't have gone. Still not starting.
2, Unplugged all main devices including power to Gfx card and still no joy.
The only option now is to take my PSU out of my other system and connect that. This isn't going to be a 5 minute job, so before I do this can anyone tell me if the PSU is at fault, why would the mobo LED be on and what could be causing this if it is the PSU?
OK, I'm back up and running! 
But can I put my finger on exactly what the problem was? No. 
However, last night before shutting down I'd basically unplugged everything and reseated. Still nothing. So just as a last thought I twisted my Tunig Tower 
slightly from side to side to see if i could move the processor in case it was a bad connection. Hey presto, after reconnecting the power cable and switching on my PC fired up and the PSU stayed on and the discs span up but no BIOS or screen output. However, this was still progress. So tonight, I dismantled everything, took out the mobo, checked just to make sure of no broken tracks or popped capacitors. Reseated the Quad Core and reapplied thermal paste. Refitted my Tuniq Tower 
recabled everything (remeber not to fit everything perfect as it may have had to come out if the problem was not sorted) then connected the basics (No printers, scanner, etc) and started it up. ASUS logo came on, went through post, started Vista in safe mode (due to the crash in first place) and went through all fine. Dosconnected and recabled everything and had the chance now to go back and cable properly from the examples I'd seen on OC forum, which now looks really smart. So, the moto to this story is:
"If you think its broken, it not always is, so don't think the worst until you've checked everything!" I'm now going to sleep! 
But can I put my finger on exactly what the problem was? No. However, last night before shutting down I'd basically unplugged everything and reseated. Still nothing. So just as a last thought I twisted my Tunig Tower slightly from side to side to see if i could move the processor in case it was a bad connection. Hey presto, after reconnecting the power cable and switching on my PC fired up and the PSU stayed on and the discs span up but no BIOS or screen output. However, this was still progress. So tonight, I dismantled everything, took out the mobo, checked just to make sure of no broken tracks or popped capacitors. Reseated the Quad Core and reapplied thermal paste. Refitted my Tuniq Tower recabled everything (remeber not to fit everything perfect as it may have had to come out if the problem was not sorted) then connected the basics (No printers, scanner, etc) and started it up. ASUS logo came on, went through post, started Vista in safe mode (due to the crash in first place) and went through all fine. Dosconnected and recabled everything and had the chance now to go back and cable properly from the examples I'd seen on OC forum, which now looks really smart. So, the moto to this story is:"If you think its broken, it not always is, so don't think the worst until you've checked everything!"
I'm now going to sleep!