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Computer won't boot, flashing power light, no beep codes

Son Goku

No lover of dogma
There's been a few odd things since I came home last summer (a cold boot, I'd have to re-seat the video card, but that was about it. Otherwise it seemed to get power and all). The (I think it is the PSU fan has sounded a tad bit off the last coupla weeks however, though it isn't the easiest place to get me ear up to to track exactly where the sound change is comming from.

Anyway, today they turned the air conditioner on in my apt complex. Problem is, previously the thermostat didn't change over from heat to A/C due to a bum change over stat that detected whether hot or cold water is in the pipes.

Despite this change, it still didn't detect it today, so I just went to change the wires (reverse them on the stat) so the stat would work right for A/C. Not wanting to get jolted when the thing would come back on (it does no doubt carry a fair amount of current) I shut down my computer (typical way in Windows with start, shutdown, and shut down the computer) in winXP Pro. Turned the circuit breaker off so I wouldn't get electrocuted and pulled the stat out of the wall, reversed them (the land lords around here took months to send maitanence when this has happened before...and either roasting or freezing as it turns on the A/C when it's cold and turns it off when it's warm, so it either never runs or runs indefinitely isn't my idea of fun), screwed it back in, and switched the circuit breakers back on.

The computer was running just fine prior, as long as I didn't shut down and reboot (above mentioned prob with no video from a cold boot), but this time, unlike before where it would run but without video, it now ran for a split second and shut itself down. The power LED is flashing green, but that's it as the power cuts (fans stop running after that second and everything).

I'm inclined to think it's a PSU problem, but am not 100% positive as I can't find any indication on what a flashing power LED means. Another thing that makes me suspect this as a possiblity, I bought the PSU with my current computer case in 1999 or 2000. The PSU is one of the oldest components in my computer at about 5-6 years old now. It's been there through several upgrades, and at this age might be nearing end of life. It's at least conceivable for an over 5 year old piece of hardware... It flashes about once every second. I can find references online to beep codes, but not a flashing power LED code.

Is this the PSU, and is this what I should replace? What does a flashing power LED indicate specifically, if not a PSU problem? Is there something else I should check? My funds are limited now, being in college and all, so I can't go around just changing everything, but if it's failed, I need access to my computer again. Any suggestions?


Beware the G-Man
Political User
But it sounds kinda like something I had a while back. Same sorta thing but mine didn't even show a screen or anything.

It turned out that my video card died. Cooling fan took a shiit and then it popped a capacitor. Also check the cooling fan on the CPU. If the CPU fan dies it will do something like you described.

Son Goku

No lover of dogma
I'm not getting a screen either. It's dead accept a second of booting where the fans run, then nothing.

The video should be relatively easy to check, if that might be a cause as the mobo is an Asus A7N266-E. As such, it has built in gfx, though only a GF2. It would be enough to rule out a video card problem.

As to a CPU fan, not sure how easily I could check that, as when the light flashes it turns everything off. Perhaps if I can hold a flashlight up to it, I could see if I could manage to see it really fast before everything starts. It does all stop in less then a second or so however...

The case is an Adtronics 7896a server case


The PSU is one that came with it, but it's not the one listed there. It's a 400 watt PSU, though manufacturer and all, I'd have to check at home again. (Not being able to boot it, having to post from uni computer pod now.)

The CPU fan, I do have a delta fan sitting around somewhere, but as to mounting it on the current heat sink (OCZ Gladiator, or was it a Gladiator II...it's been awhile), not sure the mounting screws are large enough to go through the fan. The delta is a bigger fan in terms of depth...


- Asus A7N266-E mobo (nForce 420-D chipset)
- AXP 1900+
- 512 MB (2 x 256) Corsair XMS 2400 CAS 2.0 DDR
- Visiontek Radeon 9600
- Adaptec 29160 Ultra 160 SCSI card

...mention if there are any other specs you need. The NIC and sound are what's integrated into the mobo.

thx for the info. Will check those 2 things when I get home.

Son Goku

No lover of dogma
OK, thx for the suggestions guys. The pod is closing soon. Will be heading home. With luck, I can get it to boot again tonight. Time will tell.

Son Goku

No lover of dogma
Thx guys. It's up and running for now, though I dare say this might only be a temporary "fix". This is what I found comming home.

I first booted, and aimed a flashlight, (more like a lantern I have here, powered by a 9 volt battery) into the computer case, while turning it on. The CPU fan does spin up, so that isn't the problem. It is a source of occassional noises however, so it might be wearing out however, not sure.

However, the fan over the northbridge chip (aka the nForce MCP, if I remember correctly...it's been awhile since I read up on the nForce) is completely dead. Unplugging the computer and trying to turn it manually, the fan is jammed in there pretty good, and is extremely difficult to turn now. No doubt Asus probably didn't put a good ball bearing fan on their north bridge chip, and anyhow the north bridge is without it's own cooling.

Unlike earlier, it did stay running sometimes (but not always) upon first booting. It seemed that unplugging my AGP video card made the problem worse (it happened more often, albeit it was troublesome all the time earlier). I'm gathering this could be, that when it is using the integrated video (the GF2 GTS embedded in the nForce 420-D chipset), it will run hotter then it would with the add in AGP card (another function running off the north bridge chip).

Comming up however, it then gave the 3 distinct beeps (the long one followed by a coupla short beeps) that's indicative of a video problem. This is a problem I had since last summer (also when my comp wasn't running for awhile, turning it on cold boot, the video now takes a long time to "warm up", the screen being almost too dark to see for awhile. Albeit turning off the monitor, for instance over night while comp runs, and turning it on again in the morning, so such issue).

Before re-seating the card did the trick, and when it didn't, pulling the AGP card, letting it boot up on the integrated video, and then shut down, and put the AGP back in... There might well be a video problem, but if I were to guess, not the gfx card itself, but the AGP bus, which is controlled by that north bridge where the fan on it has died. That might also fit some other issues, like if it wasn't running for awhile, first boot up, the mouse doesn't work (comes in over the USB bus) but unplugging it and plugging it back in, it will come up. Not sure, though I thought the USB bus was controlled by the south bridge, hmm...

Now, fanagling didn't help. But this is where LordofLA's suggestion came in, though APM was supposedly disabled in BIOS, if it was following settings I gave it in BIOS configuration, which it might not have been, exactly. Not wanting to look for the manual to find the reset jumper, I just pulled the CMOS battery, and left it out of the comp for several minutes. Put it back in, with the gfx card still reset, and it then booted.

It's running again and thx guys. But I don't dare assume this is permanent. A new motherboard might eventually be needed, if the north bridge is being negatively affected by the loss of cooling on it. At least my comp case runs at a lower ambient temperature then most (very large server case, and lots of fans...)


Beware the G-Man
Political User
Go out to any computer parts store and get a NorthBridge fan kit. They are usually a heat sink and fan package. Just remove yer old one and put/screw on the new one.

My Asus A8V Deluxe only had a heat sink on it. I installed a NorthBridge fan and it seems a bit cooler. Not much really (a degree or two), but every little bit helps.

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