Question No power to my msi mpg z390 gaming pro carbon ac?

[SaverBE]

My motherboard went in for repair, came back, but couldnt get it to work, no power.
Send it back and they tell me it works fine.
Try again at home when i got it back again, nothing.
Can i check if the mobo is getting power by looking at lights?
I must say this time i only plugged in the 12pin power connector to test, but no lights, not even when i tried bridging power switch contacts.
I just dont want to rebuild my whole pc without being sure there is power coming to it.
There should be a hint of life from just plugging in the 12-pin connector right?

 

[rgd1101]

full system spec? include make and model of the psu

 

[SaverBE]

Motherboard: msi mpg z390 gaming pro carbon ac
PSU: corsair hx750i
CPU: Intel I9 9900k
GPU: Msi geforce rtx 2080 gaming x trio
RAM: Corsair 32 GB DD-3000 kit
CPU-cooler: Corsair Cooling Hydro Series H150i Pro
SSD: Adata SSD 1.0TB XPG SX8200 Pro M.2 PCIe
Harddisk: Seagate 4TB ST4000DM004 5400 SA3
Case: Phanteks Eclipse P600S TG

 

[SaverBE]

Oh, i am using this PSU for the system right now,
i bought another cheap motherboard when this one went in for repair, because they told me there would be a waiting time from around 8 weeks,
and im not sitting without a usable pc for that long.
So i know this PSU works, its the same as i have been using on this motherboard before the RMA.

 

[rgd1101]

oh. you didn't put the cpu/ram in? you need those to boot

 

[SaverBE]

But will there be no sign of life by just connecting the 12-pin?
Its just that last time i did do all that, connecred everything, expecting it to just work again, but it didn't do anything just like now.
I don't want to do it all over again to come to same result and do it again to rebuild the system with the cheap motherboard i'm using now.
But if there is no other way i'll guess i'll have to, i just wanted to know if anyone knew if there would be some kind of light from just power on this board, bacause with the cheap board i am using now, there are lights on the board by just the 12-pin connector.
That board is the Asus prime z390-p by the way.