Re: Computer wont power up sometimes, runs fine
- From: "Rod Speed" <rod.speed.aaa@xxxxxxxxx>
- Date: Wed, 21 Jun 2006 20:27:20 +1000
David Maynard <nospam@xxxxxxxxxxx> wrote
Rod Speed wrote
David Maynard <nospam@xxxxxxxxxxx> wrote
dzmcm@xxxxxxxxxxx wrote
My computer has had an issue where it wont power up once it's shut down. It starts
for a fraction of a second--all the lights flash on--but then stops completely. If I
try to start again once it
flashes, I get nothing. If I switch off the powersupply for around
30 seconds and then switch it back on, the same thing happens. A short flash of
light, then nothing theirafter.
That is the classic symptom of a PSU over current crowbar.
There is no crowbar in modern PC PSUs.
I was speaking in the same terms Intel uses, as in
http://www.intel.com/cd/channel/reseller/emea/eng/244768.htm
More fool you.
"RISKS of using wrong power supply... This may cause the power supply to ?crowbar?:
Terminally stupid terminology with PC power supplys.
As for "no crowbar," you may want to inform these folks they don't know what's in their
PSUs.
http://www.voxtechnologies.com/Power_Supply/jet-280an.htm
"the build-in crowbar circuit will automatically shut down the outputs to avoid damaging
the external circuits."
Bet there is no crowbar, just more pig ignorance, like yours.
PSU senses over current and immediately clamps the output rails,
Shuts down the regulator, actually.
That's one way but not the only way.
Yes, but I bet his power supply has no crowbar.
which is why you get the light flash/fan 'bump', and the clamp won't let go (so 'on'
switch does nothing) till it's unplugged long enough for the capacitors to discharge.
Most PSUs will start fine when the bad load is removed.
Depends on the fault and which recovery mechanism the vendor chooses to implement.
Yes, and like I said, most will start fine when the overload is removed.
For over-voltage ATX specs require it be latched off.
He aint got over voltage.
For over-current it may recover on removal of the load or use latch protection.
Most do in fact recover on load removal.
Not to mention I didn't make any statements about "most PSUs." I said the symptoms he
described were consistent ('classic' because the original ATX specs allowed only a
latch) with an over-current latch-up needing a power cycle to clear, and they are.
Pity the original ATX specs said nothing about any crowbar.
I can usualy get it running within a day or two, just trying every
now and then. When it starts, it runs fine. I can keep it running
for days at a time. I can restart just fine. I don't like to keep it on when it's not
needed, so i usualy shut it off at night (unless
I really need it the next morning). I've used both stock and
overclocked/overvoltage settings with no difference. I've removed all but the bare
essentials (mobo w/1 stick of ram (either one or the other) and vidcard) and still no
luck.
Did you consider the hard drives part of the 'essentials'?
I've tested the powersupply by hooking up a few devices and connecting pins 13-14
with a wire and it works fine.
Connecting a 'few' devices to the power supply won't test the potential problem
because the potential problem is it shutting down from a significant *load*.
Indeed, and even powering a different system doesnt trigger
what is very likely a PSU fault, bad over current sensing.
It appears to be a motherboard problem.
That is unlikely. Possible, I suppose, but it doesn't fit the symptoms.
Indeed, but even everyone without exception telling him that
hasnt helped. Gunna be hilarious to see if he's got the balls to
fess up that the RMA of the motherboard made no difference.
I've tried to contact MSI, but
I can't fax and there is a problem with their support request forum
(making them usless). I can only email their RMA address (duno how
far i'll get there, i'm still waiting for a reply). I first
contacted OCZ about the powersupply and recieved excellent support
(though the power supply doesn't appear to be at fault).
My system is:
MSI K8N Neo4 (nforce 4 standard) -- lates available BIOS
Geforce 6800 PCIe
AMD Athlon 64 3200 -- excelent overclocker btw
1x512mb Kingston HyperX DDR333 (2-2-2-5)
1x512mb Patriot DDR333 (2-2-2-5)
OCZ Modstream 520 powersupply
1xWesternDigital 40gb
1xMaxtor 80gb
I would really appreciate any advice or insight I can get. Especially since MSI is
completely usless in the matter. I don't want to have
to replace my motherboard (which is less than a year old).
Try removing everything but just the motherboard/processor and see if it reliably
powers up the motherboard/processor alone. If it does then it isn't the motherboard.
Thats overstating it, there is a small possibility that the
motherboard has a fault that sees a too high initial load. Unlikely
tho and swapping the PSU is the only really viable test.
.
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