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First post, by athlon-power

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This post is about what the title suggests. When the PSU I am using for my SE440BX-2 build is plugged into the motherboard and then plugged into the mains, it will turn on without the power button being pressed. Pressing the power button does nothing, and both the HDD and power LED indicators light up solid. I am not sure if this is an instance of a failed PSU, a failed motherboard, or both.

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Reply 1 of 12, by Rawit

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Does your board have any features in the BIOS concerning powerloss? Some board have this setting that they turn on when power has returned after powerloss. That might be the issue here. Does the board boot?

Last edited by Rawit on 2019-06-11, 08:11. Edited 1 time in total.

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Reply 2 of 12, by athlon-power

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Rawit wrote:

Does your board have any features in the BIOS concerning powerloss? Some board have this setting that they turn on when power has returned after powerloss. That might be the issue here.

The problem is, it doesn't fully turn on. Only the fans connected directly to the PSU spin. The CPU fan does not spin, nor does the case fan that runs from the motherboard spin, nor is there a POST beep, or really anything at all.

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Reply 3 of 12, by Rawit

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Seems I was too quick with replying and not reading it correctly... This seems more like a PSU issue then. AFAIK with mainboards that don't post or beep one of the fans does spin, even just for a second. Can you measure what comes out of the PSU? You plugged it in the right way? It might be a short.

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Reply 4 of 12, by athlon-power

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Rawit wrote:

Seems I was too quick with replying and not reading it correctly... This seems more like a PSU issue then. AFAIK with mainboards that don't post or beep one of the fans does spin, even just for a second. Can you measure what comes out of the PSU? You plugged it in the right way? It might be a short.

"

I tested it with a little PSU tester I have, and from what I can tell the PSU is fine.

Also, it's impossible to plug in a PSU backwards with the keying it has on the connector between the motherboard and the main power connector.

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Reply 6 of 12, by athlon-power

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Rawit wrote:

Do you have a videocard and/or RAM inserted when you try to boot it? Does it have a PC speaker? Try removing all components except CPU and see if it beeps. Does the CPU get warm?

Apparently, a backwards IDE cable will cause the entire system to refuse to POST. Not sure why that is, but the cables I have are older and so they do not have keyed connectors, it can be somewhat easy to mix up the direction of the IDE connector. Thanks for suggesting that, sometimes the simplest solutions go right over my head.

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Reply 7 of 12, by athlon-power

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So, roughly a month later, I'm back in the same exact situation- this time, however, the system is doing the same thing with NOTHING connected. No video card, no other cards, no case, nothing. Just the motherboard on a non-conductive surface. Only thing that's hooked up right now is the CPU and CPU fan. No RAM. It also won't POST with other CPUs, so I doubt my 500MHz PIII is dead.

This started when I tried hooking up a Quantum Bigfoot TX up to it. I may have done the IDE backwards again, but this time simply unplugging the IDE cables does nothing. The motherboard won't POST at all. I'm considering marking this one as dead. The CPU does get warm, but neither the CPU fan or system fans plugged into the motherboard work. Only the fans plugged into the PSU directly will spin.

So, my question is, how the Hell is plugging in an IDE data cable backwards going to fry the entire board and kill it? I didn't hook any power cables wrong, all of those are keyed, and the HDD itself still seems to work.

The fact that it's done this before also is strange. Does that mean that there's something I'm missing? I don't know what to do at this point. I've tested it with multiple PSUs and the same exact thing happens every time. The PSU turns on, provides power to everything except (seemingly) the motherboard, though the CPU heatsink does get warm like it's doing something. There's no missing RAM beeps or anything. Just dead silence.
I'm lost here.

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Reply 8 of 12, by retardware

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Maybe a combination of heat wave, latent previous ESD damage in addition to the damage suffered from shorting out things.
Maybe put the computer aside, wait until weather got cooler, and then sell it before it completely breaks down.

Reply 9 of 12, by athlon-power

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I'm in North America, and right now my room is quite cool, even without air conditioning. (20c-25c ambient)

Though the ESD+Short theory would make sense.

Looks like I'm in the market for a new Slot 1 mobo. I already have a Gateway Tabor III from an old Gateway tower of some kind which would work but it's actually in its own dedicated Pentium III 600 Coppermine rig- it was just a spare before, but now it's in its own build.

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Reply 10 of 12, by athlon-power

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I know this seems like a lost cause, but the last two days I've tried multiple things with this motherboard to try to get it to work. As usual, when the PSU is plugged in, it will turn on without me pressing the power button. It will, however, turn off if I press and hold the power button in (I have a little one that is independent of a case). It will also turn back on when I push the button again. All three keyboard indicators will light up when it first powers on, and the monitor acts as if a signal is being sent to it for a split second, and then everything goes "dead." So power is getting to it, and I think the video card just starts to display something, but then it gives up.

I have tried three different CPUs, and have tried powering it up in both the diagnostic mode and normal mode, defined by a little blue jumper on the motherboard. When the jumper is set to diagnostic mode, it does the same exact thing as it does in normal mode. I tried a Celeron 333MHz/66MHz FSB, a Coppermine Pentium III 600E, and a Katmai Pentium III 500MHz/100MHz FSB. All three processors will heat up, as if they are doing something. What that could be is something I don't know. I have tried removing RAM, and it provides no beeps. Normally, this would indicate a dead motherboard, but it did this same exact thing back when I first caused it by installing the IDE connector backwards. It will not do this when the floppy drive connector is done backwards; only the HDD connector, which goes to the primary IDE port on the motherboard. It has POSTed plenty of times with the FDD cable hooked up backwards, and I turned it off and fixed it and it ran just fine.

I'm doing something wrong here, and I don't know what it is. Visually, the motherboard looks just as good as when I first pulled it out of the box- I don't see any way that it could've gotten damaged in a visible, physical manner. This only happened when I connected the Quantum Bigfoot TX drive into it- I was trying to see the size of the HDD seeing as it would spin up normally when connected to a standalone PSU. What that has to do with anything is something I also don't know.

I'm trying to fix this motherboard so aggressively because I don't think I'll have the money to buy another Slot 1 motherboard like this for a long time, and because of the fact that these SE440BX-2's now run for upwards of USD$200 on eBay, and run for a minimum of USD$100. Back when I bought it, I only paid USD$40 for it. I'd have to go through another good set of research on whatever motherboards are available on there, that is if I even had the money for one of those in the first place.

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Reply 11 of 12, by Aragorn

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perhaps try a POST card?

Have you reset the CMOS?

As for the board, i pulled a SE440BX3 out of a Dell XPS T500 which sold on ebay for peanuts, with the CPU still in it. The whole dell system was very cheap too. Worth looking into as a replacement option if the "genuine" ones are silly money.

Reply 12 of 12, by athlon-power

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Aragorn wrote:

perhaps try a POST card?

Have you reset the CMOS?

As for the board, i pulled a SE440BX3 out of a Dell XPS T500 which sold on ebay for peanuts, with the CPU still in it. The whole dell system was very cheap too. Worth looking into as a replacement option if the "genuine" ones are silly money.

I wish I had something like a POST card.

If taking out the CMOS battery for a few days at a time counts, I have. I actually do have an SE440BX-3; it's a Gateway Tabor III out of some Slot 1 Gateway tower. My problems with it are that it's in a different case (not the original, I bought it with a 500MHz PIII Katmai off of eBay about a year ago), and the front panel connector situation is quite strange so I have to remove the piece of plastic that holds the actual metal connectors in place. It's sort of hard to describe. The reason why I've been so belligerent about this is because I wanted a time-accurate sort of custom build; throwing in an OEM motherboard sort of ruins that perception, and I finally didn't have to worry about that with the SE440BX-2. I also got that motherboard new. That's one thing that's really bothered me. I managed to somehow kill a brand-new motherboard in less than a year of owning it.

I may have to suck it up and deal, and throw that Tabor III into the case, and see what I can do with it. It's about my only option now. Unless I figure out that some people were able to get ahold of standalone OEM boards when buying computer parts back then, I'll have to replace it at some point.

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