Mobo Power is ALWAYS ON and POST fails

Hi,

I'm having a very strange problem with my PC and i have no idea what it is. After trying to put in new Hard Disk and a Soundcard, the new Hard Disk was failing. I proceeded to set things back as it was and removed these items. However, now there seems to be an issue with the power ALWAYS being ON. Usually, you would need to plug in the power cable, turn on the switch at the back of the power supply, and then actually turn on the PC at the front. However, right now when i plug in the power cable and turn on the power supply at the back, the PC will immediately have power (without actually switching it on). The fans will spin and all the lights appear to be on, but i hear no beeps and nothing loads - the monitor gets no signal. I try to hold the front On button to power down but it does not respond, neither does the reset button. The only way to switch off the PC is the back power supply switch or unplug the power cable. Have searched everywhere but cannot find a similar situation. I tried another power supply and had the same problem so i suspect it is the motherboard..?? I also tried taking out the battery and clearing the CMOS but same problem. Any idea's or suggestions for what could be the problem...??

My original PC setup is as below:

AMD 3000XP+
Asus A8V Deluxe Motherboard
ATI Radeon XT6000
1GB Ram
160GB WD HD

Hi i am also having the same problem as you. I got the Asus K8N. I have stripped mine down to just the MB and Processor and still powers up on its own.

Although i still havent found a way to repair it without replacing the MB i have found a few other forums that had ideas to repair it.

the obvious one is to make sure the CPU isn't earthing. The other one is that some MB's have a metal plate on the back of the MB which clamps on the heatsink which can cause the CPU to earth. Tried booting my machine without the back plate but still same problem.

If you solve this problem please let me know.

Thanks

Hi.
I read your post and I am having the same problem.
Did you find the problem?
Let me know, Thanks.

I too am having the same prob. I was putting together a PC out of older parts to give to someone and ran into the "always on" problem. I unhooked the case switch to MB powerswitch terminal wires, figuring I'd try shorting the MB terminals, but the MB powered up as soon as the PS did. So, I switched power supplies from a cheapo to a fairly new, really good ThermalTake and the problem stayed. So I switched MB and CPUs and the probs still there. At this point I'd need to buy something new to switch and I don't know what.

When I googled the prob, this thread was the only thing close.

I hope an answer arrives soon.

fredolm

Usually when a mobo powers on and all fans go and all lights are on but nothing happens usually means a failed CPU.

Thanks aitken325i, I need to check the failed CPU theory out.

First I need to see if nothing else other than lighting up happens. As far as I've gotten so far is the powerup when the PS powers up. I've never checked to see if the PC actually works OK anyway.

Meanwhile, F y'alls I, The original setup was a Hercules 400W switching power supply, an ASUS A7V-VE with audio/video onboard, AMD T-Bird 1.4 MHZ CPU, 512mb PC100 SDRAM hardwired to the case power switch from the (correct) MB terminals.

When the problem reared it's ugly head, I unhooked the hardwire connection to the case power switch, figuring I'd try shorting the MB power switch terminals.

That didn't work, it still powered up immediatly, so I swapped to an ASUS A7A266 MB, AMD XP 1800+, Audigy sound card, an ATI Radeon Vivo 64mb video card, 512mb PC100 SDRAM.

It still powered up as soon as the PS was on, so then I swapped PS's to an Antec True 430W.

It's sort of crazy. I have pretty much a totally different PC with the same problem. I was thinking maybe the original PS shorted something in both MBs? Or maybe the CPUs?

Oh well, I can't look at it any more till tommorow.

More L8R

So are you using different mobo and cpus ?

Im in the bios now woot one thing about that dfi board you can pretty much reset them and start all over in the cmos doh on that part but Im in like flynn...

huh !?

Yup... different mobo, diff CPU, diff PS. Pretty much a different PC. Although it's the same case, same power switch. But I'm not hooked up to the power switch.

I haven't had a chance to do anything more since my last post. Too busy with other people PCs. Maybe today.

Thanks for your ideas and your patience.

And, I have no idea what "webej" is talking about, unless maybe it's that he cleared the CMOS and reset the BIOS.

regards,
Fred

If these are all new components, then I think we need to look at the case being the problem here. Do you have a spare case that you could pop everything into just to try ?

Hi aitken325i,

The mobos and cpus are all reclaimed components. The cheapo PS was new and the Antec pretty new. The case hasn't been used before, but it's a cheapie and has been sitting around my place for a year or so. I'd say it's not the most trustworthy part of this setup.

Maybe, I should try the setup "breadboard" style, with the mobo/CPU on a tabletop, hooked up to a PS, mouse ,keyboard and a clean formatted HD and see what happens. What do you think?

What I'm trying to do is build a PC out of what I have around for a friend with little money. Hopefully, I can do it without laying out too much.

Anyway, I've just learned my dad is not well at the moment, and I'm going be out of town for a couple weeks, so this all is going to have to wait.

Hopefully we can pickup then. I think I'll be back by 6/21, but I'm not sure. I'll post an updated return date from my dad's PC around 6/14.

Thanks,
Fred

Yeah, you could try it "breadboard" - that way we could confirm whether or not it is the case that is causing the problem. Does point to that though with it being new components.

Hope your dad gets better soon and just post back when you can, I'll still be around here somewhere.

Hi aitken325i, I'm still away. My dad is in the hospital with a bunch of things wrong, not the least a blood clot in his leg. I don't even know when he'll get out.