Yes, rare, but a grounded 213W power supply was a small run thing, for some kind of dev kit or something like that I read. It has the same 16.5A rating on the 12V rail as the 203W supply has, but 3x the rating for the 5V rail at 3A instead of 1A. Made to power quite a bit more 5v something or another, some ttl stuff perhaps? You could use it for usb power I guess.
Heres a listing for one
https://www.ebay.com/itm/225365240523
Label pic -
https://i.ebayimg.com/images/g/nBMAAOSwqjVjypWI/s-l1600.jpg
I'd like to see how they did it. Maybe just a few caps to ground to dump the noise? With a class 2 supply, with no earth ground, there's still noise to be dealt with. WIth an unpolarized supply, there is a 50/50 chance to be significant "touch current" (low current, considerable potential) when parts of the power supply designed to deal with that fail. (and a little bit in working order). Converting it to a grounded class 1 supply is something I'm considering, though not anywhere near set on doing.
I wouldn't doubt if the 203w original supply was more stout. I have seen a schematic and a video of the 175w supply, and just at a glance, it's quite a bit different than my 150W brick.. (1 big mains filter cap compared to my 2 small ones, the most obvious thing.) Probably all I will change is to increase the voltage ratings and increase the probably the capacitance at the output. I'd be really nice to see schematics of all of them though.
I had thought about using a power supply from a computer. That would probably be the best option for the cleanest, most long term reliable power source. It would be nothing to use the 360's power on signal to fire a transistor on the power on input to an atx supply.
I did manage to flash my lite-on drive without any special equipment, I found a video called "the hillbilly way" to flash....
I don't know if it's part of the "capacitor plague" but the green sanyo filter caps that I had a few bad confirmed visually on my board, which I'm replacing, I've found more than one other post about those caps being bad specifically. Them first or the ones in the power supply? I don't know, but they work on the same rail, so they help each other out, or stress each other more when one fails.