BIOS doesn't POST after adding sata cable

zhengchenji18

Prominent
Feb 1, 2018
2
0
510
BIOS POST issue:

If I plug in only the CPU and motherboard cable from PSU, MOBO has BIOS post.

As soon as I add a SATA cable connecting to SSD, the BIOS doesn't POST. The BIOS_BOOT_LED is red. Tried resetting by pulling out the battery for 10min still doesnt work.

Question:
I am trying to figure out which part is bad.
Is it the PSU or the MOBO?

This is a system that has been working for 1 year already. Suddenly, one day it shut itself off. I unplugged everything to test.

Specs:
Z170-A ASUS
6500k CPU
SSD
 

zhengchenji18

Prominent
Feb 1, 2018
2
0
510
changed PSU, it works now.

I am a bit surprised cause the PSU passed the paper clip test.
Is there any other way to test and confirm PSU is faulty?
I only have this 10 year warranty PSU for a bit over a year.

Also, how does the RMA process work for cosarir?