My motherboard don't support my powersupply?

[encise]

Hello, I just bought a new motherboard and cpu wich is MSI Z370M , With the cpu I7-8700K
And my powersupply is couger powerx 550W bronze, I just gave my pc to one of this local stores and he told me your motherboard do not support your powersupply, i said wtf why, he said 550w its good but the powersupply it self don't work with ur motherboard, Im really confused maybe he is scamming me i don't know he said you should get a new one wich support your motherboard, is that correct? and my powersupply really dont work with my motherboard, and by the way when he runs the pc some red light turn on in the motherboard and after moment's its go off again, please guys i really need help asap because idk should i get a new powersupply or?

 

[clutchc]

He's scamming you. Ask him what was the incompatibility.

 

[encise]

He's scamming you. Ask him what was the incompatibility.

i did, he said the 550w works fine, but this powersupply is too old, you cant use it on the new z370m motherboard,

 

[encise]

Thanks guys, the powersupply was really old i just go to another guy and he said the same thing, i got a better psu and then its worked