New build wont launch/Orange indicator

[HappySquid69]

Hi,

first time poster, first time builder here! I was following the building guide on the LTT channel and when doing the open bench test my Asus motherboard first cycled through all the indicators (presumbaly while checking their existance?) after which the orange indicator labeled "BOOT" lit up and didnt turn off or blink. I have done all the troubleshotting advice provided in the video and I do not believe it to be the Ram or the cpu or the gpu. i plugged the gpu cable into a slot labeled pcie and the cpu cable into P8. not sure if thats already my mistakr since those seem to be the only  slots that fit the respective adapters. another issue i could imagine it being is the fact that my psu came with only one 2 times 4pin cpu cable for an 8 pin slot on the mb, however my mb has 2 8 pin slots. i have tried awitching them around but to no avail if anyone has an idea what might be going wrong, id highly appreciate any advice. 

ill be back in roughly an hour, my food is ready. 

thx in advance!