Question PC wont boot with any CPU overclock after working for months?

[gwdope]

So I have been running a 4.9 GHz OC on an i5-9600K/z390 Aorus Elite, for months and all of a sudden I cant get it to post with any overclock, it will only work at stock settings for the CPU. The memory can be set to XMP profile but any change to anything with the CPU will not boot. I have run memtest and it found nothing, I have run 12 hr. of Prime95 with the stock settings and it passes, I can play my games just fine (minus the boost I had from the OC). I have tried a windows restore and then updated windows to the latest build, I've updated all the drivers I can find. I'm wondering if there's anything I'm missing trying before I do a clean Windows install (Don't want to do that if I can help it because I don't want to have to re install everything) and failing that start replacing expensive components. What should I do?

Specs:
i5-9600k
Z390 Aorus elite
GTX 1070 ti
Seasonic Focus+Gold 650 FX
850 Evo 250GB (Boot drive)
Crucial M.2 500GB (Game drive)

Edit: When the OC was working my CPU temps were in the 60-65C range with intense gaming and I had a high of 76C when running Prime95 to test it, so I really don't think I fried any thing on the CPU.

 

[Lutfij]

Are you on the latest BIOS update for the motherboard? You should ideally create your bootable installer for Windows 10 using Windows Media Creation Tools and an 8GB pen drive. I'd also ask you to manually source/install the drivers for your platform, as opposed to automatically downloading the drivers via the OS.

 

[iSteven_6s]

I would suggest flashing the BIOS first. If that doesn’t work, try taking it to a repair shop and having them try a new motherboard...

 

[gwdope]

Are you on the latest BIOS update for the motherboard? You should ideally create your bootable installer for Windows 10 using Windows Media Creation Tools and an 8GB pen drive. I'd also ask you to manually source/install the drivers for your platform, as opposed to automatically downloading the drivers via the OS.

I have not updated the BIOS for the mother board. Do I need the bootable installer for windows 10 to update the MoBo, or is that for a clean windows install in case the BIOS update goes sideways?

 

[gwdope]

I would suggest flashing the BIOS first. If that doesn’t work, try taking it to a repair shop and having them try a new motherboard...

I'm a long way from any repair shop so anything is going to be DIY. I do have a HS