Intel i7-9700k upgrade for 5680 desktop?????

I've been doing a lot of research regarding this upgrade and I found conflicting info, perhaps accurate info in their time-line.

Has anyone done this upgrade here? Or know of someone that can share some light? 

In the thread bellow, a member explains why it should be possible due to a BIOS update. 

BIOS upgrade link in this post. 

Having a motherboard Z370 w/the latest bios 2.2.0 it should be possible. I mean all other Z370 boards take 9th gen CPUs, why Dells shouldn't? Right? 

Here is the BUT... I found out that if you have an i5-8400 like me, the motherboard may not take 9th gen CPUs... thus why I am here, trying to find a definite answer.

Thank you.

PS: I am running a 700watts PS and a GTX-1080ti. So I have power cover and I will be willing to get an upgraded cooler for the new CPU. When I game, all the stuff I am running on the background is getting the  CPU to over 90% at times.