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When I press the power button on my desktop, it does not power up completely. Before I press the power button, I see lights on the motherboard. Everything is normal. On power button press, the fans on the cpu, graphics card and motherboard start to spin a little for a second or two and then they stop. No beeps during this process.

It has been doing this for a while now but it used to start up after some trials. Once it starts up, I have NO issues at all like random shutdowns so it is not an issue with OS.

Update: I left the desktop off for a few days and it started.

I'm just guessing here but it seems as if the PSU (Antec TP2-550ATX) is dying out and does not have enough power now - just a guess. It's an old desktop assembled in 2005 but I have maintained it well.

Update: I always keep the desktop running and I never shut it down. During updates or manual restarts, it powers up without issues. I wonder if this sheds lights on the issue.

Any idea how I can narrow down the issue? ex: if I can find if the PSU is dying etc. I'd really like to fix the issue. Please help. Thanks.

Below is the complete configuration.

DFI LAN-Party UT NF4 Ultra-D 6/23 {6.70},
Evercool EC-VC-RE 41/47C,
AMD Opteron 170 2.0GHz {} 1.312V 36/41C, 
ThermalRight SI-120, Panaflo 120×38mm
OCZ Platinum 2×1GB 200MHz 2.66V 3-3-2-7 1T
XFX 7800GTX 256MB 475/1250MHz {91.31}, 
Zalman VF900 Cu led 41/56C
WD Caviar 320GB 7200RPM 16MB SATA 3Gb/s
Antec TP2-550ATX
Antec P180
WinXP sp3
Logitech MX310
Razer Mantis Speed
BenQ FP91G+ 19" LCD 8ms DVI
Creative Audigy2 ZS {4.42}
BenQ DW1640
Logitech z-5300e 5.1 280W

Driver versions: {}
User settings: []
Voltage: V
Wattage: W
Temperature: C (Celsius) min/max

Update: I had bought a new PSU and I think it either worked only for a few days or did not work (I can't remember). Finally I concluded that the motherboard died and gave up.

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Power on for a moment then off was an issue I recall with P4 comps and not connecting a certain PSU cable to the motherboard. I know yours is an AMD, but anyhow, in your case you say it turns on completely sometimes so that's not it. And if it stays on when on then I guess it isn't the power cord. But swap the PSU. – barlop Jan 8 '11 at 20:28
If you have alternate PC's at home to use not so keen on getting replacement parts right now, I'd try leaving the affected PC off for about a week and try again. I had a similar problem where some components were not working immediately (the video card). The problem corrected itself after leaving it off for 5 days. And it turns out I happen to have the same brand PSU too. – Jeff Mercado Jan 8 '11 at 23:54
Update: I left the desktop off for a few days and it started. Ah, the ol' turn it off and back on trick. – Jun 16 '13 at 8:56

10 Answers 10

up vote 2 down vote accepted

I had this exact problem with a Corsair PSU I bought a month ago. It will power on for a second or two, then everything would shut off and it wouldn't even try starting again until I had flipped the breaker on the PSU on and off. Replaced it with another PSU and everything ran just fine. A clear defect in my PSU that caused it to trip its internal circuit breaker after a second or two of power up.

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Obviously, try swapping the power supply. If you don't do that, then you may never narrow it down. If you don't have a spare one then a techie friend might.

It's your best hope and maybe your only hope. That's what anybody fixing it would do.

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With problems that only happen when a system is fully warmed or cooled, loose components are always a strong suspect. Carefully reseat the CPU, RAM, expansion cards, and all power connectors. Heat will cause loose connections to fail sporadically due to expansion and contraction of the components. (With the expansion cards, CPU, and power connectors you can just press them in to place to make sure they are properly seated. With the RAM, you need to pull the clips off the modules and then press the module back into place and be sure that the clips reattach themselves. Obviously, as with any time you do work inside the case, follow proper ESD precautions.) [1]

This could still be a problem with the power supply as suggested above. Swap with a known-good power supply or (better) test the power supply with a decent power supply tester to get a conclusive result on whether the power supply was at fault. (preferably one that will report the actual voltages with a load applied).

In rare cases I've seen a malfunctioning drive cause these sort of problems,. After ruling out the power supply, the next time the problem happens, try booting the system without the hard drives and optical drives connected. (Be sure to save this until after you've checked out the power supply - the drives pull a lot of current especially to spin up when the system is starting- so not only can a bad power supply easily make the drives misbehave, but also taking the load of the drives away from a failing power supply might be enough to cover up a problem with it and confuse your troubleshooting.)

[1] - Yes, I'm aware that the clips on the RAM modules are supposed to prevent chip creep. But my experience has been that it does still happen, particularly with systems running at higher and higher operating temperatures.

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I had the same problem and I used to employ a simple workaround.
In my case, the problem occurred only if I started PC using the power button.
What I did was configured the BIOS to "Always turn on" on power loss.
And that fixed my problem. It used to take a lot of time at some times, but at least I did not have to keep pressing the power button.

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Sounds like it is either the Power Supply or Motherboard. Check to see if any capacitors on the motherboard are out of shape; meaning the tops are rounded or rusted. Do not touch since this is acid coming out.

The other advice to change the Power Supply out with a friends to see if the problem resolves. This helps isolate if the problem is with the existing supply or not.

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Empathizing intro:

I had exactly your problem with a Supermicro E-ATX motherboard: all the tachometric fans would pulse for a moment both during power up and down, while the DC fans spun normally; when this happened, all subsequent boot attempts failed; leaving the power cord unplugged for a few hours allowed it to temporarily recover.

Problem spotting:

It turned out the PSU was underpowered: the 12V rail measured 11.4V with a 1V ripple; during CPU bursts (64 threads of gcc) it dropped to 11.2V, below the 5% allowance. This was measured after the PC successfully booted. The boot itself probably failed due to high HDD spin-up currents, which for my 3 HDDs was a 90W peak (each drive can absorb more than 30W during spin-up).


After removing one of the HDDs (a 13W HGST), the boot would be successful at any further attempt. Obviously, the permanent solution is to replace PSU.


A condensed summary, or quick mind-dump:

  • when boot failed, fans spun but PWR_LED wasn't lit;
  • low mean PSU voltage and high ripple signify overload;
  • I should have checked the PSU gray wire (PWR_GOOD)
  • after a failed boot attempt, subsequent boots would fail even reducing the load (no HDDs plugged, lesser FB-DIMM RAM modules mounted); only unplugging the power cord for a while would reset the hardware state.
  • the PSU used to work well with the same hardware, for all its past year; it's always been underrated for the hardware it had to drive, but probably got worst with aging: Taiwanese caps wear out with time and resistors with heat.
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See my answer here : Any way to tell apart a CPU defect from a mainboard defect?.

If you can hear the fans, then it is probably not a PSU problem.
If you do not get any beeps, then it is probably a motherboard problem.
But as it does start up sometimes with no problems, this is an intermittent problem.

The possibilities are endless, and probability is not enough to justify buying any part.

Try to follow the script described in the on-line book link that is in my above answer, to check for RAM problems, bad contacts etc. If you cannot find anything on your own, my best advice is to decide whether you wish to see a tech-shop about it, or invest in a new computer.

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I had problems like this for several months. My computer would boot, start booting or complete booting before the power cut out and it (occasionally) rebooted. Then it stopped turning on at all. I tried replacing the motherboard, making sure there were no shorts between the motherboard and the back case (I had installed an aftermarket CPU cooler and the screws were touching the case). I had tested the power supply multiple times using a procedure provided by the manufacturer and it worked each time the problem occurred again. The PSU eventually failed completely and I was able to RMA it. Keep in mind, though, that power problems can be CPU, Motherboard or PSU related (or even power button related). You should try to make sure that a number of other things are working before you try to replace a part.

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You should check your SMPS 20/24 pins connector first, Sometime the pins or cable getting loose of this connector. You can check it by replacing with new SMPS.

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Normally,when power button initiates the supply and then everything blacks out-sometimes this cycle repeats-is associated clearly with the motherboard connecting end of the power button cable extention.There is a six pin connector at the end which connects to the mother board.This plastic piece is lossely connected and or is broken-cracked.Result is on and off connection to the mother board-which triggers the power on and off-Otherwise the operating system will be working fine. Solution-Call an expert and ask him to change the plastic six pin connector-if possible.If this problem is not set right there is chance of mother board getting major repairs. regards to one and all. venkatraman

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