What are the chances the parts I get come broken?

1st thing, DOA is less and less every year and decade. It's never been so good as far as quality vs price...however. DOA is always a part of every production.

highly depends on the lot # of (in my case motherboards).

One of my first IT jobs was building dev systems and I built about 5 a week.

Three weeks in was perfect, week 4 (iirc) we got a batch of DOA boards (all warrantied but it didn't help that week) and after a few months we started to build a redundant store of parts.

There will be bad lot#'s on everything from RAM to SSD's to even SATA cables. I've seen it all. It's not merely one thing.

The most reliable things I've seen (to me) have been power supplies and low profile, plain-jane RAM... the less flashy and less shiny the more reliable it seems to be. to the point where if I see shiny, flashy ram the first thing I think of is "they can't sell it without that crap on it" and always look for specs over shiny.

Buy it all at once (or at least have it delivered all at once) and take your time, ground yourself, and you should be fine.

/r/buildapc Thread