Question New CPU, No disaply

[ItzDreaMz]

Good evening guys, I'm having a bit of an issue with my PC. About a year ago, my old i7-7700K died on me, not sure how or why but it did. I didn't have the money to get a new CPU at the time so I substituted an i5 in there and my PC worked fine just a lot slower. This year I was able to scrounge up the money to get another i7-7700K which I did. I took out the old i5 and put in the new i7. However, once I tried to power everything on, I got a screen showing that a CPU change had occurred, obviously. Well I didn't have a keyboard plugged in right away so while I was scrambling to get my keyboard plugged in, the screen changed to black. I thought I would just restart and catch the screen again, but it never came back. Now when I turn on my PC, i'm greeted with a black screen, not just a normal black screen though. My monitor is recognizing the input and is displaying all black, the pixels are lit up but just black.

I did some research and found this could be a number of things. 1) Out of date BIOS 2) Power supply issue or 3) CMOS
1) Out of date BIOS: From what I found, this seems to be the reigning champ of solutions for this issue. My plan here was simple, swap the old i5 back into the pc, boot into BIOS and M-FLASH a BIOS update. This is where the situation gets more interesting, after swapping the i5 back into my PC, i'm getting the same black screen issue.

2) PSU Issue: I don't think this could be an issue but maybe my PSU isn't pushing enough power. This doesn't quite add up considering I've ran the exact same specs before and never had an issue like this

3) CMOS Clear: I tried clearing the CMOS as well. Power everything down, pop the CMOS battery out for 5-10 minutes, pop it back in then power up. No joy on that end either

Any help is greatly appreciated, i'm really trying to recycle this PC for my nephew and I don't want to have to build a new PC for him

Specs:
GPU: EVGA GEFORCE GTX 1070
CPU: Intel Core i7-7700K
Motherboard: MSI Z170A Krait Gaming 3x
PSU: Corsair RM 550x

 

[RAIDGoblin]

was the i7-7700K new new, or second hand?

can you get bios with either CPU's if you are pressing the key required to get to bios?

have you tried with the video cable plugged into integrated graphics and no GPU?

have you tried with different RAM/different RAM configuration

how did you test that your old original CPU was broken, did you try it in another system? because it's always possible that your mobo or PSU was what had the fault and couldn't deliver enough power for your i7, putting in an i5 with a lower power requirement might have given it a year more life

do you have a different known working PSU you could try it with?