Things like multi-phase power, higher end capacitors that handle more heat and last way longer, "over" engineered power sections, BIOS settings that are made more for the long haul as far as stability and how fast certain timings are pushed. Generally the chipsets that are chosen and the things enabled with them are geared for general servers too, not multimedia daily use, and that alone can stabilize not just the hardware, but the OS too.
Some of that stuff you’re starting to see in even some more budget-friendly "gaming" boards, from companies like ASRock (ASUS). There’s some gaming boards now with 16 phase power sections, higher end caps, several heat pipe coolers on chipsets and power regulation amps, etc… so at least OEM built home computers are catching up, if you’re willing to spend a few bucks more (and end up with a product 2-3 times as good as brand name pre-built).