I somewhat wished they’d gone to 48vdc instead of 12vdc, though to further reduce cabling, but I guess that would be a big change, the 12vo seems much simpler
components use 12v, 5v, or 3.3v in pcs currently. why do the step down from 48->12 instead of running 12v naturally? 12v is also what is used by the most power hungry components of a PC (GPU).
The GPU voltage is also step down to 1-1.5v by graphics cards VRMs.
There shouldn't be an intermediary step down to 12V. Google's been doing direct step down from 48V->~1V with GaN fets for half a decade, which is vastly more power efficient than the two step 277V->12->1V that many server systems go through.
It'd also be amazing to have usb-c extended power (48v) be something we could just add for free, essentially. (Alas this is complicated by needing to step down to lower voltages too, necessities some semiconductors in the delivery path to usb-c, which would have some voltage drop. This strongly implies to me something more like 52V or 54V would be ideal instead of 48V.)
For anything that typically runs under 100W, I agree that 48V is ridiculous. But I would love love love to see some motherboards for ThreadRipper that have GaN fet for direct conversion from 48V, or stuff like that. It'd be pretty niche. But it should be an option!
One of the big potential winners could be people with solar; being able to run your system directly off your solar bank would save double digits percent of power, versus inverting then converting back.
You're right that in the immediate term we'd see a lot of intermediary conversions. I'd love to have a better game plan, for not just motherboards but other components to expect either 48v or wider voltage inputs. Non-trivial to support 10-60V but if that was a market expectation & not a niche need we'd see very affordable solutions spring up practically overnight. There's already a range of usb-c focused power converters that are exceedingly cheap that could step in for this need!
Edit: seems like Google is using two stage conversion primarily, but not necessarily 4:1 48V:12V. Their fixed ratio converter seems to have a 6:1 mode (8V) target as well, or be configurable for even bigger ratio (they said up to 12:1 in their talk). As of 2019, a bit of change of tune from original 2016 ambitions. Good talk? https://youtu.be/aBkz2JR4UVs
It depends on the current. Your 48 V suppply won't supply microamps, but Amps.
In fact the exact opposite is true, it is safer in practice. In a true fault condition into flesh the currents involved aren’t substantially less safe (4x microamps is still microamps). With protection circuitry and current limiting, the permitted currents are that much lower, which is easier to deal with.
which are cut because of costs.
An additional issue is that the sweet spot for voltage conversion is around the 1:10 ratio. Going 120V -> 12V -> 1.2V makes a lot of sense, 120V -> 48V -> 1.2V less so.
I don't buy this at all. 48V and 96V are standard telecom DC voltages. Those parts already exist.
If anything, this would be a big boon as it would enable using both telecom and consumer parts interchangably (thus increasing volume on both).
You use a 100K resistor if you really need to keep things at 0402 for 100V. (P=V^2/R = 0.1 watt)
A 0.1uF 0402 ceramic cap rated at 100V is half a cent.
The biggest problem are your power transistors with max Vgs. That requires a bit of care at 24V; requires quite a bit more care at 48V; requires very specialized topologies at 96V.
So the solution is to.make 75 % or even 100 % of the mainboard, the PSU. /s
Its like a code refactoring
Mains power is dangerous and should be kept in a box separate from current limited lower voltage DC, which could be on the mainboard instead.
Nothing actually needs 12v, it all just converts locally to the desired voltage which is why the mainboard is already a psu