PC won't boot or post, not sure what to try next

**Specs:**

> i5 3570K > >Coolermaster T2 (?) CPU cooler > > ASUS P8H77-M motherboard > > EVGA ACX 3.0 1070 > > 16 GB DDR3 RAM (2x Ballistix Sport, 2x EVGA Superclocked) > > WD, Hitachi, and Seagate HDDs > > Corsair AX 750 power supply > >Windows 10

**Issue:**

This morning I tried to wake my computer and was greeted with a nonresponsive white screen. Clicking and moving the mouse did nothing. Eventually I pressed the power button to force a restart, and no response. Finally, I hit the switch on my power supply, flipped it back, and have been unable to boot since then. No post, no bios, nothing. No fans, no response at all.po

**Things I have tried with the same result:**

I checked multiple times, everything was plugged in.

I tried multiple power outlets and cords.

I unplugged every single periphery (including MKB and screens)

Removed the GPU, RAM, and hard drives.

I pulled the power supply out, [tested it](https://www.youtube.com/watch?v=5FWXgQSokF4) and it worked. Used an older replacement power supply (it works) but had the same failure to post.

I reset the CMOS, pulled the motherboard battery and replaced it.

I removed the motherboard from the case, set it up on a card board box, connected only the power supply, and was unable to boot while jumping the power pins.

**One final twist:**

I plugged in the older PSU's 24 pin connector to the motherboard, but didn't plug in the 8 pin CPU connector. I was unable to post, but it momentarily powered up before shutting off. I was unable to replicate this with the Corsair PSU.

What should I try next? Is there anything else before taking it to a professional?