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Old 09-03-2008, 02:27 PM   #1 (permalink)
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Default strange power problem: no boot, LED flicker, angry floppy drive

Hi all....

First, a little prelude to the main problem.

A couple of weeks ago, I came back from vacation, plugged in my computer (I normally unplug everything before leaving) and turn it on to discover it would not boot: all fans would turn on, my two optical drive LEDs would flicker on briefly, but the system would not get to POST. I tried the usual troubleshooting: disconnecting everything one-by-one until it was just the mobo with power connections and the CPU (even took the RAM out), still no luck -- not even system beeps. I don't have a voltmeter, nor am I power-savvy, so I concluded my motherboard was dead and happily went shopping for a bunch of new stuff. Since my hardware was so old, most of it had to be replaced with the mobo, to bring it up to modern-day specs. Now the config is:

CPU: AMD Athlon 64 X2 5000+ 2.60GHz dual-core (new)
CPU heatsink/fan: Noctua NH-C12P CPU cooler (new)
motherboard: Asus M2N-SLI (new)
RAM: 2 x 1024MB OCZ Platinum Revision-2 PC6400 DDR2 800MHz dual channel (new)
video card: EVGA Geforce 6200 256MB DDR2 PCI video card (only bought it because mobo doesn't have on-board video, dang) (new)
PSU: 350W Antec one that came with the case, I'm pretty sure this is it: - SP 350 Specsheet
hard drive: 160Gb SATA 3.0Gb/s Samsung SpinPoint
other peripherals: Promise 2-port SATA 3.0Gb/s RAID controller card
case: Antec SLK3700-BQE
case fan: some 120mm Antec fan that came with the case

Now, the real problem...

Last night I finally assembled everything, powered the system on, looked in the BIOS -- it even booted far enough into the OS for me to conclude that at least the hardware was working (Win XP however is not very tolerant of major hardware changes like this). Yay! But some weird things happened:
  • After powering down using the button in the front, case fan and PSU fan did not shut off, although CPU fan did. I had to flip the PSU switch in the back to turn them off.
  • Power LED never lit up.

Then, I decided to move a HD LED connector since I had the wrong one hooked up -- my case has 3 HD LEDs and they're not labeled clearly, so I tried hooking up one of the other ones (this is purely cosmetic stuff). Also fiddled with the power LED since it wasn't on before. Didn't touch anything else. Now, when I flip the PSU switch in the back, the following strange sequence of events happens:
  1. Case and PSU fan come on right away (this ain't right since you need to push the power button for this; but recall they didn't shut off when powering down even when the system was "working").
  2. The HD LED starts to flicker really, really fast.
  3. After a few seconds, my floppy drive starts clicking very rapidly and loudly.

This is all before I even push the power button on the front! Oh yeah, and when I do push the power button: nothing happens, except that the CPU fan jerks really briefly, but does not start.

It was working a second ago, now it doesn't. I tried disconnecting the floppy drive and optical drive, but the LED still flickers when the PSU is on.

Some other relevant info:
  1. The power supply fan is controlled by one of those 3-pin connectors going to the motherboard. The case fan connects directly to the power supply by splicing into one of the 4-pin connectors, so it can't be regulated by the mobo at all (don't ask me, Antec made it that way).
  2. There is a LED on the mobo that turns on when you get power, so the PSU seems to be providing power.
  3. The power hookup from PSU to mobo is a 4-pin 12V ATX connector for the CPU power and the 20-pin connector for everything else. The motherboard takes a 24-pin connector. After doing some research, I concluded that you could put the 20-pin connector into the 24-pin slot, as long as you align it correctly, since the extra 4 pins are for PCIe, and I don't have any PCIe cards, so I figured I would just do this until I could buy a "proper" PSU.

What could be going wrong? How would you proceed troubleshooting this?

I am suspecting my PSU fried my old mobo and it's now out to get this one, too. These symptoms are really weird, it's as if the power is cycling very rapidly as opposed to being constant... I think.

Another question is whether my PSU is sufficient for the new configuration, but from reading some of the other threads, I think it should be.

Oh yeah, side note in case anyone is wondering why I have a RAID card with 1 drive plugged into it, well, it was because my old mobo didn't have SATA and the RAID card was cheaper than just a plain SATA controller due to some sort of sale... and now my HD is JBOD and I need to copy the partition off it for backup before I start messing with installing stuff for new hardware.


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Old 09-03-2008, 05:55 PM   #2 (permalink)
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Default Re: strange power problem: no boot, LED flicker, angry floppy drive

Oh boy lot of things happening here..
Well I would check those connectors once more.
Then I would check if my PSU is good. If so I would disconnect the
whole thing and start over.


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Old 09-03-2008, 07:15 PM   #3 (permalink)

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Default Re: strange power problem: no boot, LED flicker, angry floppy drive

Phew you're good at writing descriptive problems! No spelling errors that I see either good job! I'll give you a shout when I need some essays written for college .

My guess is static electricity. You didn't ground the case after you flipped the connections and when you sent power through the computer again it went. If the power button does not work anymore have you tried swtiching it back to the way it was before?

To test the power supply turn the switch off on the back first and disconnect the connections from the motherboard. Take the 24-Pin motherboard connection, grab a metal paperclip and jump the green wire connection and any of the black wire connections together. Then turn the PSU on. Don't worry this just activates the PSU and will NOT shock you . If the PSU turns on, your motherboard is fried. If it doesn't, grab a new PSU instead.

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Old 09-04-2008, 01:38 AM   #4 (permalink)
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Thanks for the advise. I haven't tried y'all's suggestions yet (like shorting the PSU with a paperclip), but I have an update to my situation.

I sat on the problem for 24 hours, then came back to it today, plugged my computer in, flipped on the PSU switch, push the front power button, and it booted! But when I turned it off via front power button, instead of powering down, it went back to its weird state: case and PSU fan on (but CPU fan off) floppy drive clicking, hard drive LED flickering very fast. If I turn the PSU switch off and back on, it comes back to this weird state immediately.

After cycling through this several times, I discovered a "fix" -- turn off the PSU and let the computer sit for a while (a few minutes). Then it will go back to normal, but not for long, as it seems like if my system works for a little while (a few mins), the problem rears its ugly head again -- all I have to do is power off and I go back to the flickering/clicking.

Just for fun, I decided to power it down and let is sit there and click for a few minutes. The loudness of the clicking died down after a few minutes, but the flickering and fans persisted. Then the clicking returned to about half-volume! WTF? So here I have box sitting here, I'm not touching it at all, it's supposed to be powered off, yet it's as if it is going through moods?

My other idea is that maybe the power button in the front is making it go to some suspend mode that isn't working quite right with the PSU. I'll play with the suspend settings in the BIOS and investigate.

The power LED not turning on turned out to be because I connected the 2-pin connector backwards due to bad labeling on the Antec case, so this is now fixed.

Oh, one interesting things I came across in my, um, research. Maybe this will be of use to someone.

To rule out a bad power switch, switch the reset switch and power switch 2-pin connectors, then use the reset switch as your power switch and see if the problem goes away. Doesn't really affect me since my power switch does seem to work, but I thought it's a neat idea.
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Old 09-04-2008, 07:36 PM   #5 (permalink)

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Default Re: strange power problem: no boot, LED flicker, angry floppy drive

Have you tried flipping the power and reset? Also have you tried just turning the power switch connection around?

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