System won't respond to Power Switch

Hello.

I ran into a problem - I can't start my new system at all: when Power Switch is pressed _nothing_ is hapenning, even cpu/system fans are not moving for a split second.
And I just was at the shop where I had bought everything - they started it without any problems, might I say they used their own PSU - I'm reusing mine from the previous build and it's functioning well - I just got back to my old mobo+cpu and everything is ok.

Specs:
-Motherboard: Gigabyte Z97P-D3 (in manual it says it requires at least 500W, my PSU has 550 and is certified as gold 80+)
-CPU: Intel i5-4690K
-PSU: Seasonic SSP-550RT
-RAM: 2x8Gb Kingston 1600Mhz Red Fury

I guess other specs are irrelevant (two fans, 1 ssd and hdd, video). I even tried disconnecting video card power - didn't help.
I also tried reseating ATX and ATX 12V (there are 2x12V connectors/cables on mobo and PSU), flipped around the power switch pin connector - even tried touching pins with a metal screwdriver - the system doesn't respond at all. I'm baffled, does anyone have a suggestion? Thank you.

Not trying to insult intelligence or anything of that nature but the switch on the back of your psu is on as well when you try to start your PC correct.

Reading what you wrote, I'm gathering you tested the Psu on the old system and it worked?

even tried touching pins with a metal screwdriver

Click to expand...

Your saying you shorted the power pins on the motherboard, to try and get it to start?

rayraysfunhouse said:

Not trying to insult intelligence or anything of that nature but the switch on the back of your psu is on as well when you try to start your PC correct.

Click to expand...

No problem, basics are the most important Of course I switched it on (and off, and on...).

Mandrake4565 said:

Reading what you wrote, I'm gathering you tested the Psu on the old system and it worked?

Your saying you shorted the power pins on the motherboard, to try and get it to start?

Click to expand...

Yes, I've posted this using my old system with fully functional PSU.
Yes, I guess I shortened the pins on mobo, didn't know the correct English term for that.

Ok break down of where my brain is:
The system worked at the shop where you bought it, with a different Psu.
You bring it home and it will not start at all.
You take the Psu out and put it in your old system and it works fine.
It sounds like everything should be working then, have you tried re installing the Psu and see if it will work. Maybe when you first installed it one of the pins was not making good contact.

I'm thinking the same as Mandrake. If your psu worked on a different system and the shop had yours working with a different PSU I don't see any reason your PSU wouldn't power this one.

You got it right Mandrake. Alright, thanks guys, going in for another try to make it work!

This was kinda strange - apparently when I connected some unknown connecter (I have 4 fans in chassis, so there are loads of cabling), which I assumed was one of the fans, to sys_fan_2 pins, the system couldn't be started (even with me shortening the power pins with a screwdriver). So I just left out this sys_fan_2 and everything is OK. I'd guess that connector being connected created some sort of power loop and prevented system from booting, who knows.

Thank you all for your input, I'm glad I figured it out!

Glad it is all figured out. Next step is overclocking...wait what did I say that