HPz420 power

[str8_whiskey]

I have a HP z420 motherboard that I will be using as a server. I have a cooler master case tower. The power supply is a thermal take tr2 connected with an 24-18 pin adapter.  As far as I can tell I have the power switch connected correctly (do the make an adapter). However, I am still not getting power. I've checked the switch on the power supply  in both directions it still doesn't turn on. There is an 8-pin power connecter on top of the motherboard, do I need to use that one also? 

Here is the board I've purchased:

https://www.ebay.com/itm/165827933208

Here is the Case:
https://www.coolermaster.com/catalog/legacy-products/cases/elite-430-black/#specifications

[DGroves]

if you look at the z420 motherboard  by the front memory slots there is a a 8 pin connector

this is the CPU power connector (+12/ground) and the board requires this to be connected along with the 20 pin connector in order to power on

i recommend you use a multimeter to confirm which row of pins are ground before connecting the atx supplies cpu pwr connector

the z420 service manual will also have the board connector pinouts dl it from the HP site

[str8_whiskey]

I just realized today that I missed the 8-pin on top, it said CPU MEM so I thought RAM. My case doesn't leave a lot of room for that connector.  

[DGroves]

you will also have issues with the front usb connections and the system fans speed  unless you use the original HP cables

or are willing to create custom replacements for these items

[str8_whiskey]

 As of just trying my 8 pin connector on top, it's still not working. From what I can tell the rear power switch button will power it on correct?  

As of watching this vid, he just go it to work. He made it look easy
https://www.youtube.com/watch?v=DpJViwtct5g