PC components DOA

How often is it that a PC component will be DOA?\
How often for ram?
most ram is never doa...most time it have a bad bit or two that shows up under memtest. most times with ram it work or not work do to bios bugs on some mb. on a new build post and update the bios then let it sit in the bios for 20 min if the cpu temps are fine reboot and post from a usb stick with memtest86 on it. run memtest on it overnight if it fine then install windows.
How often for cpu?
it happen once in a blue moon. just like tv and other parts when you make a lot of parts one or two parts can die.
How often for gpu?
with gpu as long as it shipped well. most gpu like cpu are not doa. there can be bad ram on the gpu that can fail when stressed.
How often for storage?
standard drive fail a lot. used to work for emc corp. used to fail out a lot of standard hard drives a lot. have seen whole box of drives sound like lawnmowers that were dropped. the newer ssd drives as long as they have good firmware on them they dont brick. there have been bricking issues with ssd and bad firmware over the years. most ssd have a set life of reads/writes. as long as you watch how your ssd ages (data writes) you wont be caught in the end when your ssd goes into read mode only then bricks if the power is turned off. i have an intel 520 ssd that a few years old and still going fine.
How often for psu?
power supplys most time have same fail rate as hard drives there two main failing issues with power supplys. one is shipping damage the other is parts failing or power supply that are not rated as stamped.

cheap power supply most times are not rated for what there stamped for. for giggles google power supply failures/explosions you see a lot of cheap units blowing up when load tested.
shipping damage....as a tech over the years in seen units cases crushed or fans bent or broken on shipped units and have had the old cap rolling inside the unit or other metal part over the years.
on most newer power supply a doa unit most times is one with a cap or a failing leg. most time when these doa units show up some of the pc will power on but the voltage output on some of the legs are below atx spec.

with new buiilders or tech most issues are bent pins or plugging cables into wrong ports on the mb and damaging the mb or power supply. over the years you see people that have snapped ram clips off or ripped video card slot from mb. best one was when i worked at micro center was a person used a lighter to see how his 3.5 inch floppy was jammed and set the case on fire.