PC keeps switching off on start-up

  • Thread starter Thread starter Tony Tee
  • Start date Start date
T

Tony Tee

Hi,

Is this the right place to ask some advice on why my pc is shutting down
when i boot it up?

Would also be nice if you could just recommend a good newsgroup to ask in,
if this one isn't appropriate.

Basically, when I switch it on, if I don't hold my finger on the on button
(for a second or two), it will start to boot for 1 second then switch
straight back off again.

When it does switch straight back off again, it won't start when I re-press
the on button to get it on again unless I knock off the power at the mains
for 5 seconds, and try again.

Sometimes, even when I have kept my finger on the on button, it hangs as its
booting, or even switches off on its own, about 2 minutes later after
seemingly starting up fine.

Usually though, when it works, it works, and won't switch off and I can
leave it on for hours on end with no probs, its just the starting the pc up
I am starting to get probs now.

This morning it took me about 7 attempts to get it to stay on, it was just
cutting out almost immediately aftyer switching it on.

XP pro operating system, medium spec PC about 3 years old, well maintained
with re: software and anti-virus/spyare etc

Cheers for any insight on this matter.

Tony
 
any beeps from the machine when it shuts down? you checked the fans are
turning on the cpu when it shuts down? you could have a clogged up cpu fan,
and now and again it manages to get going and the machine runs. (try turning
the machine one with a case side off to see what is happening inside). Have
you moved the base unit recenlty, you could have knocked some of the
hardware inside loose, maybe the cpu needs re-seating.
 
| Basically, when I switch it on, if I don't hold my finger on the on button
| (for a second or two), it will start to boot for 1 second then switch
| straight back off again.
|
| When it does switch straight back off again, it won't start when I re-press
| the on button to get it on again unless I knock off the power at the mains
| for 5 seconds, and try again.
|
| Sometimes, even when I have kept my finger on the on button, it hangs as its
| booting, or even switches off on its own, about 2 minutes later after
| seemingly starting up fine.
|
| Usually though, when it works, it works, and won't switch off and I can
| leave it on for hours on end with no probs, its just the starting the pc up
| I am starting to get probs now.

Other than for this, it seems your power supply might have a problem.
It still might, where some wire is touch another possibly due to damaged
insulation. If might not touch it at times due to mechanical vibrations
and not short out.

I had a power supply burn up due to a short in a coil winding. When the
short happened, the current flow went way up and things got real hot real
fast. At that point it was doing what yours did. But after about 6 tries
to get it going, I heard a pop, smelled smoke, and it never came on again.
Disassembly showed a big molten spot on the coil (it could have been the
transformer). I replaced that PSU model in all my computers that had it.


| This morning it took me about 7 attempts to get it to stay on, it was just
| cutting out almost immediately aftyer switching it on.
|
| XP pro operating system, medium spec PC about 3 years old, well maintained
| with re: software and anti-virus/spyare etc

It's not an issue with XP. It might be an issue with the BIOS, but more
likely it is a hardware problem with the power supply being highly suspect.
 
Kardon Coupé said:
any beeps from the machine when it shuts down? you checked the fans are
turning on the cpu when it shuts down? you could have a clogged up cpu
fan,
and now and again it manages to get going and the machine runs. (try
turning
the machine one with a case side off to see what is happening inside).
Have
you moved the base unit recenlty, you could have knocked some of the
hardware inside loose, maybe the cpu needs re-seating.
Click to expand...

Thanks for the reply.

I starts up for 0.5 seconds then switches off.

No time for any beeps! The times when it switched off 2 minutes after boot
up there was no beeps either.

I haven't opened the case yet but I can tell you that I hear the fans
spinning up as it starts.

I don't think it is getting too hot either, I used to suffer with that
before, (was warned with the pc beeping) and had an extra fan professionally
installed to suck/expell air through the case, its not given me any warning
beeps since.

The CPU fan was recently repaced too.

I'm scared to turn my pc off now, cos when it works, it works! On and on,
its when I switch it on thats the problem!

Tony
 
why my pc is shutting down when i boot it up?
Click to expand...

Happened with my current PC 3 years ago.

Discovered the Power-On button was jamming 'in'.

Learned to press it much more gently!
 
Hi,

Is this the right place to ask some advice on why my pc is shutting down
when i boot it up?

Would also be nice if you could just recommend a good newsgroup to ask in,
if this one isn't appropriate.

Basically, when I switch it on, if I don't hold my finger on the on button
(for a second or two), it will start to boot for 1 second then switch
straight back off again.

When it does switch straight back off again, it won't start when I re-press
the on button to get it on again unless I knock off the power at the mains
for 5 seconds, and try again.
Click to expand...

Having to disconnect PSU from AC mains in order to get it to
work again is normally a sign the PSU safety shutoff circuit
kicked in, and that either the PSU is insufficient for the
system or has suffered a failure degrading it's function.
Since initially powering up a system is often more stressful
than powering an already running system, it is not uncommon
to see this happen even if the PSU could have continued
running the system once it managed to turn it on - although
often the condition gets worse until it won't run at all,
and running in this state can pose a risk to the powered
devices in some situations.

Sometimes, even when I have kept my finger on the on button, it hangs as its
booting, or even switches off on its own, about 2 minutes later after
seemingly starting up fine.

Usually though, when it works, it works, and won't switch off and I can
leave it on for hours on end with no probs, its just the starting the pc up
I am starting to get probs now.

This morning it took me about 7 attempts to get it to stay on, it was just
cutting out almost immediately aftyer switching it on.

XP pro operating system, medium spec PC about 3 years old, well maintained
with re: software and anti-virus/spyare etc
Click to expand...


That's not a very comprehensive description of the system,
ideally we'd have a better idea of specific brands and
models in case there were some specific issue effecting
something, and to arrive at a generalized idea of the power
requirements of the system versus the specific PSU
make/model/rated-current.

PSU would be the first suspect.
 
That's not a very comprehensive description of the system,
ideally we'd have a better idea of specific brands and
models in case there were some specific issue effecting
something, and to arrive at a generalized idea of the power
requirements of the system versus the specific PSU
make/model/rated-current.

PSU would be the first suspect.
Click to expand...


The system is 3 and a half years old, with a newer motherboard put in last
year.

Its a Q-Tec 450W Dual fan (gold) ATX PSU
The motherboard is a ASROCK K7NF2-RAID
Athlon 2500 Barton CPU

On taking the side of the case and powering up, I have noticed that the fan
on the underside of the PSU doesn't turn, whilst the one on the outside of
the case does.
 
The system is 3 and a half years old, with a newer motherboard put in last
year.

Its a Q-Tec 450W Dual fan (gold) ATX PSU
The motherboard is a ASROCK K7NF2-RAID
Athlon 2500 Barton CPU

On taking the side of the case and powering up, I have noticed that the fan
on the underside of the PSU doesn't turn, whilst the one on the outside of
the case does.
Click to expand...

Q-tec is commonly considered to be overrated junk. I'd
consider it the primary suspect. I doubt the failed
bottom fan is the problem, probably it's low true
current was, and that (along with cheap capacitors)
caused a failure from those caps. Even so, if you
were to repair it, the fan ought to be replaced
too.
 
|> That's not a very comprehensive description of the system,
|> ideally we'd have a better idea of specific brands and
|> models in case there were some specific issue effecting
|> something, and to arrive at a generalized idea of the power
|> requirements of the system versus the specific PSU
|> make/model/rated-current.
|>
|> PSU would be the first suspect.
|
|
| The system is 3 and a half years old, with a newer motherboard put in last
| year.

Should have put in a new PSU at that time. Or at least now. Try to get
quality brand this time.


| Its a Q-Tec 450W Dual fan (gold) ATX PSU
| The motherboard is a ASROCK K7NF2-RAID
| Athlon 2500 Barton CPU
|
| On taking the side of the case and powering up, I have noticed that the fan
| on the underside of the PSU doesn't turn, whilst the one on the outside of
| the case does.

That should indicate where the cheaper (you get what you pay for, or less)
parts are concentrated.
 
Tony Tee said:
Hi,

Is this the right place to ask some advice on why my pc is shutting down
when i boot it up?

Would also be nice if you could just recommend a good newsgroup to ask in,
if this one isn't appropriate.

Basically, when I switch it on, if I don't hold my finger on the on button
(for a second or two), it will start to boot for 1 second then switch
straight back off again.

When it does switch straight back off again, it won't start when I
re-press the on button to get it on again unless I knock off the power at
the mains for 5 seconds, and try again.

Sometimes, even when I have kept my finger on the on button, it hangs as
its booting, or even switches off on its own, about 2 minutes later after
seemingly starting up fine.

Usually though, when it works, it works, and won't switch off and I can
leave it on for hours on end with no probs, its just the starting the pc
up I am starting to get probs now.

This morning it took me about 7 attempts to get it to stay on, it was just
cutting out almost immediately aftyer switching it on.

XP pro operating system, medium spec PC about 3 years old, well maintained
with re: software and anti-virus/spyare etc

Cheers for any insight on this matter.
Click to expand...

Could it be some sort of mechanical or electro mechanical problem?
I seem to remember having a similar problem on an older machine.
Have a look at the switch mecanism maybe it could be cleaned?
(think its a micro switch though).
I think It happened after I installed some 'new' memory (second hand).
Might be some poor contacts somewhere which work better when
'warmed up', try reseating memory?
I think I sorted it out somehow but I forget.

basically if it not software it be mechinacl/electrical?

goodluck
 
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