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Computer Starts When I Turn Power Switch On

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September 17, 2008 6:38:10 PM

Hey folks - I just put aqnother new 500w Thermaltake power supply in - when I turn it from "0" to "I" on the back of my case - my rig automatically starts up , even without any power switch, reset, etc plugged it the motherboard.

Is this a BIOS reset and/or should I remove battery for 1 minute, then try again.

I have rechecked all connections, both to power sources (20 pin, 4 pin to mobo) and hardware connections

I originally believed I had a RAM issue, which would not power up my monitor, have made many changes, testing etc - but this has me baffled.

P4C800E Deluxe
Intel 3.2 HT
ATI 1600X AGP
1.5GB Kingston PC3200 RAM
2 x 40GB Maxtor Hardrives

Thank you in advance.
Odie1941
September 17, 2008 7:07:26 PM

Odie1941 have you plugged up the power switch and the reset switch since then?
September 17, 2008 7:11:16 PM

since?
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September 17, 2008 7:14:11 PM

No - I initially had those switches plugged into the mobo - thats when it first happened, incrementally unplugged all switches "power, rest, led, etc) and it still happens.

As of now - nothing is plugged in to mobo and once I hit it from "0" to "i" all fans, mobo green light, ec all start up automatically.

Still wont turn on a signal to monitor, will get to that step, hopefully.

Two things that did happen before new power supply was put it - I took out the battery for a full 3 minutes, though didnt jump andything, just took out the battery - and my old power supply literally blew up. Is it possible mobo is fried also?
September 17, 2008 7:20:28 PM

Odie1941 if you just unplugged the the battery for 3 minutes that shouldn't blowed the psu.the old psu could have fried the motherboard and that's why it is powering up with out any headers plugged up to the motherboard.check on motherboard for and caps to see if any of them are puffed up on the top of them.
September 17, 2008 7:27:38 PM

Interesting - the old psu blew up because I had a 125v wire , instead of a 250v wire that came with it, recipe for disaster, lol. Heard a pop, saw a bright light than said a prayer.

I do have another mobo I can throw in (P4P800)- but before I do that (time consuming) are there any other potential solutions? Should I try to manually reset the BIOS, reset battery, etc.

Again - the original issue 2 days ago was my monitor was not receiving any signal - of which I now know - should have checked RAM sticks first, instead of almost killing myself via psu...

Not looking for an "easy out" - just want to see if there is anything else to do first.
September 17, 2008 7:31:48 PM

Odie1941 I would first check to see if any caps are blown on the motherboard and go from there.
September 17, 2008 7:41:52 PM

I see nothing out of the ordinary - swapping out old P4P mobo now - appreciate the advice and help - noticed processor sounded "odd" upon start up - unplugged all Harddrives, used 1 RAM stick, etc - still fires up when I turn back switch up automatically

Thankyou again
September 17, 2008 7:47:03 PM

Odie1941 you can google beep error codes and that will tell you what that odd beep was probably.glad the other mother board worked for you.
a b B Homebuilt system
September 17, 2008 8:31:41 PM

Yup, you could just have some slight damage to the motherboard. I'll give ya an easy solution though. Go to Costco and by a two pack of power strips. It's got a nice long cord so you can place it somewhere easily accessible. Plug your power supply into that and when you want to turn on your PC just flip it on.

:lol: 
September 17, 2008 8:52:13 PM

Does the system POST? If so in the bios there should be a power state option that allows you to turn on the system automatically after power failure. Shoule be a few options like last state, power on, power off
September 17, 2008 9:40:35 PM

No POST, no monitor signal - these were the initial problems that began the cherade. I have now blown a psu (no biggie, $20), got a new one - and literally just did 50 or so compilations of swapping at vid cards, RAM, hard drives, processors, mobo's, etc - thanks everyone.

I believe I will just bite the bullet and build a new SLI system. A good friend has a 2.4 Core 2 Duo processor - have a case thats just fine, 500w psu, need to grab RAM($65 - 2GB Kingston kit), new PCI vid card ($75)and an SLI mobo($80). Have 2 80GB Samsung hard drives in an old Dell, DVD, Floppy, etc. SO - god willing drop $250 and should be up and running by Monday. Of course, need to run it by the soon-to-be wifey...

Thanks again folks!
January 1, 2009 2:34:45 AM

I'm having the EXACT same problem, however it started seemingly at random, starts when powered on, and no video signal of any kind.

Was it the motherboard which was the culprit?

Thanks!
October 15, 2011 4:22:59 AM


Did you solve the problem? My motherboard has been wired (untouched) for three years. It has always powered on and off normally via the case switch. I recently bought a new psu (cooler master) and the board began to boot as soon as I flicked the power switch.(Without pushing the case controls) The PC still powers off normally through windows until I push the case button to reboot. I thought the psu was malfunctioning so returned it and purchased a Corsair gold series power supply. It's doing the same thing. I can't detect any wiring issues or motherboard damage. Performance of PC is the same as it was before the mystery boot situation. No big deal but I'd like to know why. The best answer so far is the bios option to reboot after a system power failure. Anyone have any answers?
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