Motherboard won’t turn on even after new psu

[Austin_17]

A couple days ago I turned my computer off for the night. The next day I went to turn my computer on and it turned on, but I got no video signal. I troubleshooted everything and still couldn’t get signal. Let it sit. A couple hours later it turned on got signal but 15 minutes later lost signal. I troubleshooted everything again , but couldn’t get it to work. I let it sit over night untouched & went to power it on in the morning & it wouldn’t even boot. I suspected it was the psu failing so unplugged it and hooked my psu from my 3d printer an ATX 450w psu which had the green and black wire cut and tied together automatically starting the psu when plugged into the wall. And all the components started up but the cpu because this psu didn’t have an 8 pin. I decided the psu was broken and bought a new one plugged everything in went to start and it won’t boot everything’s plugged in but I have no clue... can somebody please help.

 

[Austin_17]

Also I have a Z270 series motherboard, an i7 7700k cpu , a 1080 FTW2 edition gpu, 16 Gv corsair lpx vengeance ram, and a cx 750w m Corsair psu

 

[Dugimodo]

As a test try it without the graphics card and use onboard graphics temporarily. This does two things - it reduces the load on the PSU and eliminates the graphics card as the problem but with a new PSU if it works then it points to the graphics card in this case.

Go over all your connections again, if it still doesn't boot try shorting the power button pins on the motherboard momentarily (or if it has an onboard power button try that) to make sure it's not the power button itself. Make sure the PSU is turned on (happens). Try carfully shorting the green and black wires on the 24 pin with a small u shaped bit of wire or a paper clip.

If none of this does anything it may be time to condsider the motherboard but without spare parts available you might be better off taking in in to a shop where they can test things individually rather than just buying parts on a best hunch basis.