After changing power supply, motherboard still doesn't start

Even though the fans are running it doesn't mean the power supply is ok. Buy a PSU tester or bring it to a computer shop to have the power supply tested.

You are the owner of a desktop PC that has developed a sudden and catastrophic hardware
fault - probably on the motherboard (since even the ROM BIOS doesn't give evidence of its
existence), but possibly in the power supply.

Desktop PC power supplies are (relatively) easily replaceable, so if you have as many spare
power supplies lying around as I do, try replacing that first - if that doesn't fix the system, then
the problem is on the motherboard.

Since your power supply is alive enough to light the power LEDs on the system unit tower and
also the keyboard, the problem is probably on the motherboard - look at it - there may be an obviously burned visible component - but there usually is no visible sign of the fatal failure.

The reason I do not suspect your HDD (hard disk drive) has crashed is that ROM BIOS
executes at (power start) boot time right out of motherboard-mounted ROM, independent of
whether or not the HDD is functional - and since not even the BIOS message appears on your monitor, I therefore know that the boot sequence has been interrupted long before the computer becomes intelligent enough to find and access a disk drive, and then command it to try to find a
boot sector.

How to fix the computer: isolate the boot problem to the motherboard. Replace motherboard.

Check for voltage at the tip of the power connector.
If there's power there, try removing the battery and powering it up.
If that doesn't work, you can try a new power supply, but get a written guarantee that if the unit doesn't work, that you can return it.
If a new power supply doesn't fix the issue, even with a new power supply, then chances are unless you are an electronics technician/technologist, you aren't going to be able to repair the unit yourself.
Most places will want to replace your motherboard - don't use these shops.
Find a place like www.SuperTech-IT.com that does component level repairs and can evaluate and repair the motherboard rather than replacing it.

Try swapping the power button connection with the reset button connection. Then to turn on your computer you will need to press the reset button. If that works you have a faulty power button. Otherwise try using a different PSU. One that you know works. If that doesn't help the motherboard will have to be replaced.

Make sure your power supply is set for the correct region you are in, if that does not work, check the obvious stuff like your monitor having power and being on and all that. If that doesn't fix it your Motherboard is likely fried and you will have to replace it

even though its new could still be bad processor, power supply, or the motherboard its self.try to jump it without the power connected. should be pin 4 and 6. double check that though in your manual.jump it with a wire but dont touch any other pins or you will fry the MB.

Sounds like there is a short on the motherboard that is keeping it from starting or even accepting external power.
My suggestion: a new motherboard is probably in order.

turn off power and reinstall the jumper in normal mode position

Hello,

There are only two ways this can go for you.

One- you need a new power supply

OR

Two, you need a new mother board

You can verify the power supply by checking it on another machine

If the power suppy is good

And you do not hear the bios beep- then you are looking at a new motherboard- I would double check the powersupply first- most stores that sell them will let you check before you buy a new powersupply.

I had the same problem, I unplugged my computer to move it before it had fully powered down. It wouldn’t start and all I got was the flashing lights.

I asked a friend who suggested I remove the power to the motherboard then reinsert it while it’s hot. Here’s what I did. Unplug the computer. Touch something metal so you’re grounded and don’t create a static shock on the motherboard. Now GENTLY pull the 16pin wire harness off the motherboard. Now plug the computer power cord back in. Then GENTLY plug the motherboard back in. With any luck the fan will start up and the computer will begin booting up. It seems to be some type of problem where the power supply doesn’t recognize the motherboard so it doesn’t do anything until it “sees it”? Probably some type of a safety to prevent motherboard burnout?