[hatsunearu]

The "Thundervolt" reference in that post is a project where they cut up a Wii PCB to leave just the DRAM and the processors on the PCB, and then they slap an external DCDC board on top of that cut up PCB to provide power to it, while also undervolting it since you reduce the IR losses.

https://bitbuilt.net/forums/index.php?threads/thundervolt.62...

That is pretty insane.

[Nition]

Here's some more info on the motherboard and what can be trimmed off and/or replaced: https://bitbuilt.net/forums/index.php?threads/wii-motherboar...

[monocasa]

At this point I'm a bit surprised that nobody has created a netlist of the board and simply reinstalled the relevant chips on it. There has to be more density that can be eked out for easier that way than carefully taking a Dremel to an existing board.

[maronato]

There are a few reasons for it: - the cut board is compact enough for most/all hobby projects

- you can get Wiis for very cheap nowadays, perhaps cheaper than the parts themselves

- the original board makes heavy use of serpentine tracks. If they are not just to equalize track length, it’d be very hard to account for all delays in a redesign.

ofc I’m not a part of the community so their reasons might be complete different

[Eduard]

is there a goal in undervolting? Is it about minimizing the energy consumption of a Wii system? If so, how much did they save?

[Cloudef]

The kawaii forum post says the undervolting allows them to passively cool the wii

[01HNNWZ0MV43FF]

IR losses? Never heard that one

[0l]

I believe he means I²R losses in resistive elements

[NavinF]

No I think he literally means IR losses. ie voltage droop V=IR

Modern VRMs also reduce output voltage when the CPU draws more current. That way when the CPU later draws less current, the voltage doesn't inductively spike up and damage the CPU. Overclockers call this LLC (load line calibration), but don't google that because electrical engineers don't use that term and most articles and reddit threads explain this ass-backwards. Google "Active Voltage Positioning" instead to find correct documentation.

If your VRM is close to the chip, voltage droop will be ~0 and LLC can be ~0. This allows you to undervolt more and save power without instability. This is probably why most server CPUs have voltage conversion inside the chip (FIVR, Fully integrated voltage regulators)

[hatsunearu]

Yup, all of what you said is correct.

[mikepurvis]

Which would reduce heat and therefore make it easier to cool in a small form factor.

[hatsunearu]

The heat dissipated on traces is significant, but not that significant.