Member Avatar for DrWaffles

This is a bit long, so thanks in advance to those who choose to help. It's an odd problem and I just want to give you all the info I have from the get-go. :)


First off, my specs:

  • Antec Neo HE 550w PSU
  • Asus P5B Deluxe WiFi/AP
  • Intel Core 2 Duo E6600 @ 2.4GHz
  • 2 x 1GB DDR2-800 SDRAM (Corsair XMS2)
  • EVGA GeForce 8800GTX
  • WD 74GB Raptor HD
  • WD 320GB HD
  • Pioneer CD/DVD-RW
  • WinTV-PVR-150

By the way, nothing is overclocked.


The problem:

Whenever I press the power button on my computer, the power LED flashes for about half a second and I hear some of the fans start to spin up, then stop. It usually doesn't fully power on the first try. To retry, I need to either hold down the power button as if I wanted to do a hard reset, or flick the switch on the PSU off/on. It sometimes takes an upwards of 50 tries to power the machine on. And when it does power on, the machine works perfectly.


Here's what I've done so far in trying to determine the exact cause of the issue:

I have tested the PSU by disconnecting all components except two hard drives and a case fan (as a load). I jump-started the PSU by shorting the green lead to any ground. When I flicked the switch, it turned on immediately. So I suppose it's not a PSU problem.

I have removed all components from the motherboard except the CPU. The PSU has nothing else plugged in other than the motherboard. I hit the power button and the machine turns on and stays on -- it complains on POST that there's no video card (one long beep, two short beeps), but I'm happy that it powers on.

So now I put the video card back in and connect the PCI-E power cables. I try to power the system on and I get the same symptom that I described in the first paragraph: the power LED flashes for a split second and the fans turn on briefly.


So what could be the cause that would cause the computer to turn on occasionally?

Defective video card? I can run graphically intensive programs -- games, mostly -- without problems.
Maybe the slot on the motherboard is faulty? But then again, when the computer works, it works flawlessly.

Also, does anybody know of a way to bypass that missing video card POST error? Would it be possible to boot without a video card? I was hoping that I could SSH into the machine and grab whatever I need off the hard drive. This motherboard does not have an onboard graphics chip, unfortunately.

Thanks for reading all of this, guys :).

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Dani AI

Generated

This thread documents an intermittent no‑start where the front panel flashes and fans spin only briefly. later reported that swapping the PSU cured the problem; had suggested checking the power switch or PSU, and noted a similar failure mode. The behaviour described is classic for a marginal power supply, but there are a few practical checks and quick explanations that help make sense of it and avoid wasted parts-swapping.

Simple reasons a PSU can act this way: weakened electrolytic capacitors and thermal wear reduce the supply’s ability to hold voltages during the initial inrush. The motherboard waits for the PSU’s “power‑good” (PWR_OK) signal; if that signal never asserts or the +5VSB/+12V rails sag when the GPU is connected, the board will shutdown almost immediately. Intermittent connector contact, a failing front-panel switch, or PCB shorts can produce very similar symptoms, which is why a short checklist is useful.

  • Safety first: unplug mains before touching connectors.
  • Quick switch test: momentarily short the two power‑switch pins on the motherboard; reliable starts point away from the switch.
  • Easiest definitive test: try a known‑good PSU; if the problem disappears the original PSU was marginal.
  • Meter checks (for those comfortable with them): verify +5VSB present when the unit is off, and measure +12V/+5V/+3.3V under a modest load; watch for large voltage droops or no PWR_OK within a few hundred ms.
  • Inspect for bulging capacitors, burnt pins, loose GPU power leads, or damaged molex/SATA/PCIe connectors. Try a minimal-boot (CPU, one stick of RAM, video) to reduce variables.

When a swap proves the PSU is at fault, replace it with a quality unit that has ample +12V capacity and good reviews for ripple and longevity. If problems persist after a verified PSU swap, then the motherboard or a shorted peripheral should be the next focus.

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Member Avatar for mechbas

Replace on/off switch and/or PSU. Your stated you "flicked on the switch" but negelected to state which one.

Member Avatar for SMBB401

I have a PC with the same problem as DrWaffles. Anyone have any suggestions?

Member Avatar for DrWaffles

After getting a PM from SMBB401, I thought I'd mention the solution here for anyone else arriving at this thread via Google or elsewhere. I cannot edit my initial post, so excuse me for the bump.

It turns out that it was, in fact, the power supply. I bought a new PSU and have encountered no further problems.

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