I have just replaced my PC Motherboard because my old one was self booting upon switch on. Even with no wires attached at all with the exception of the main power cables it switched on when power was applied.
Now I find that my new motherboard is doing exactly the same thing.
Could it be that the power supply has a fault which causes it to do this....?
I feel I have spent money for nothing.
James
The power button maybe stuck in its hole or become faulty. ;-)
If the replacement is a quality make and model and the original was a cheap "no name" - then the money was well-spent.
However, there is a mobo setting which determines how the machine responds to a power fail. I suspect that yours has been set (changed?) to reboot automatically on power restore. Hence it will boot whenever power is applied. The solution is to change the setting.
-- Sue
Forgot to mention the reset might be doing it?
"Even with no wires attached".
I would guess he means the power cables and straps? after all it wouldn't fire up without the power switch attached. ;-)
I refer you to my previous answer. If no wires are attached, then the reset switch or the power switch cannot be the problem.
The "problem" must be on the motherboard. It could be a misplaced jumper but the odds are that it is just a bios setting.
I refer you to my other post. :-)
I can't recall the exact details (like pinouts) right now but the ATX power connector carries +5V, maintained 5V and a "power up" line. The maintained 5V is used on the mother board to power circuitry which can switch the power supply on (not just the power switch but also LAN etc). IIRC it signals to the PSU by connecting the "power up" (or whatever it's formally called) line to 0V. It could easily be that the line is shorted to a 0V pin. The ATX pinout is available on line. Google.
Alternatively there are a few BIOS setting which alter power up behaviour. Have you been playing with them?
Check the BIOS settings. Many allow you to configure what happens when power is first applied - turn on, remain off, or revert to last-known state.
Easy way to check - let the machine boot and initiate a shut down. If it stays turned off then it's almost certainly not a PSU-related 'triggering' issue.
Mathew
Erm, that was rather the problem that he was having...
The ATX power switch is very far removed from the "big red switch" of old.
The power supply contains an auxiliary supply that is always on, when the mains input is present.
If the BIOS is set to automatic boot on power restore, motherboard circuitry will detect the presence of the auxiliary supply and send a start signal to the main supply - much in the same way that the "power switch" does.
Yes, it will. And obviously is. The power switch is not connected via the main 20/24 pin connector, is it? And that's all he has connected.
There is no difference between "power switch not connected" and "power switch not pushed" as long as the switch is not stuck. It's a momentary push button.
However, as previously stated, a BIOS setting that says "start when power applied" or "revert to previous on/off state" (the latter assuming a previous state of "on") will not even *look* at the power switch state; it'll just turn the system on.
Read the damn post again, its doing it on both boards
Tsk!
So both boards are set to boot on power restore. Next.
Sue, I would like to thank you and all the other contributors who replied to my thread. Sue, you were the first to get the problem solved for me. The board in both cases was an ASUS and both have Phoenix Bios on. Both boards did have the Bios set incorrectly and as soon as it was altered, both boards worked perfectly. I never usually play around with Bios settings for fear of upsetting something that I know nothing about but will remember this saga for the rest of my life. Thanks again James
YVW. But there is nothing special in my suggestion arriving first. People respond as and when they read the post and the way news messages disseminate means that many can be answering "first", as far as they know. The main thing is that people are willing to stick their neck out and try to help.
Glad you have it sorted.
You can adjust the settings in the BOIS for mains on or off or last state when power applied etc...
Usually done by hitting the DEL or F1 or F2 keys during start-up..
Good:) However don't be scared to adjust anything in there you need to adjust. Experiment with an old machine and make notes of what you did so it can be undone.
Yes and no. Alter some of the settings (I'm thinking chipset settings etc.) and you can brickifiy your PC, so you just get a black screen when you power on, so certainly be careful.
And that is simply solved by using the CMOS reset jumper for a few seconds ...
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