So, after coming home today I wanted to fire up my PC for some sweet gaming. Guess what, nothing happened.Therefore any help in finding the problem would be greatly appreciated.

As for more detailed instructions:

- Pushing the main power button does nothing. Nothing at all.

- On the Mainboard, a little light called SB_PWR is blinking constantly (and rather dimmly, but that might just be my imagination)

- the USBs have enough power to get some devices blinking, but not enough to eg. charge my mobile.

- The main switch at the back of the PSU shuts down all of the lights. (Don't know if that is relevant.)

That is about it.

What can it be and how can I find out what to replace?

If the power supply does not even power up (with fan running), i'd say you'd need a replacement power supply)

Could be power supply or your motherboard, from the sounds of things.

Best way to check the PSU is to grab another one, connect it, and see if the rig will fire up. If it doesn't, then you may have a dead motherboard.

The latter is what I'm afraid of most.

Any good advices on a PSU?

My first assumption would be power supply. BUT, I also had a PC that would randomly shut down and restart and it turned out it was a bad motherboard. I learned this after trying to change the power supply and seeing no change.

Good luck!

Do you have a motherboard speaker? They will emit different pitches/paces of tones to indicate detected issues. A key would be in your motherboard manual. Also, does your CPU fan spin when you try to power on the computer?

One with a high number on the 12V rail.

I have to check the manual on the speaker thing.

The fan does not spin at all (neither PSU nor CPU).

Is there a manual button the motherboard? Maybe the tower button is down (fat chance, I know...)?

Edit: The board is a M3N78 SE ASUS board

I'm guessing that this "PWR" light on motherboard says that something is wrong with power supply :P

I think you can pull the power supply out of the motherboard temporarily to see if the power supply works or not. While it's disconnected, see if it powers on. If it does, but not while in the motherboard, you'll know it's the motherboard.

I'm not an expert, but I think Corsair makes some good ones. I've certainly been happy with my Corsair HX520. Of course, you'll probably want a bigger one than that.

But how do I start it when not connected to the mainboard?

You have to short two of the pins on the ATX connector to get it to start while not plugged into a motherboard.

http://pinouts.ru/Power/atxpower_pinout.shtml

Additional info:


- The main switch at the back of the PSU shuts down all of the lights. (Don't know if that is relevant.)

It's strange because i have powered up power supplies without the motherboard pin connected before. Have power supplies changed over the years?