[toast0]

> The 5 V and 3.3 V step-down converters in the PSU are pretty much only for Molex/SATA-connected peripherals, and those don't use 3.3 V anyway (99.5 % of them), since it's not guaranteed to be there.

Yeah, not only is 3.3V not guaranteed to be there, the latest rev of the SATA power spec reused (at least one) of those pins as a signal to inhibit spin-up; used for power sequencing in large disk arrays, with the fun side effect that if you've got a PSU old enough to have 3.3v on sata power, and you use a hard drive new enough to support spin-up inhibiting, you need to either tape the pin, or cut the orange wire, or you can't use your disks.