Staring at a tower and already mentally ordering a power supply is basically a personality test for techs, and we all fail it. That pinched SATA cable is the perfect example of why the boring answer is usually the right one, because a wire rubbed to bare metal against a drive cage is about as obvious as it gets once you actually look. The urge comes from experience too, since nine times out of ten it really is the PSU or the RAM, so the brain just skips straight to the ending it already knows. Problem is that tenth time humbles you in front of a customer and you eat the cost of a part you never needed. What works for me is forcing a first pass with no tools at all, just eyes and a flashlight, before anything comes out of the case. It slows you down enough to catch the dumb stuff first.

My buddy's uncle hung board in the 80s and he said those old numbers were real but only on wide open stuff like warehouses and strip malls with no cuts. He told me the trick was they'd have a whole crew loading and stacking right at your feet so you never stopped to grab sheets, plus the board was way lighter and you could just nail it. On a house with closets and stairs and a hundred outlets you're never sniffing 1,200 and nobody back then was either.