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PSU Adaptor Hypothetica Qn

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November 25, 2008 12:08:34 PM

I am sure there is a good answer for this, i just cant figure it out!

Why is it that we have so many different connectors to a PSU?
For example SATA, Molex, 3 Pin, 20+4, 6 pin and whatever i missed.
I believe all these can be converted from / to Molex, Mobo connector aside.

So why dont we just have Molex running from the PSU, with the socket on the device requiring power having a Molex -> whatever internal adaptor?


Thanks in advance for satisfying my idle curiosity
November 25, 2008 12:11:58 PM

What I would like to know is how a SATA drive can be powered by a 4-pin molex or a 10+ pin SATA power connector - why does it need so many to do the same job with only 4 wires leading to the plug?
a b ) Power supply
November 25, 2008 12:19:03 PM

You might want to PM Zorg with this question.
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November 25, 2008 12:25:29 PM

1st.. the SATA spec for power allows 3.3v for power, but desktop drives (and most laptop drives ATM) only use 12v and 5v. the tiny little contact area each of the pins provides is not enough alone to supply enough current to the device (molex connectors, however crappy they may be, are at least capable of handling more current). However, when you add a few of them tiny little contact paths together, you get enough capacity to operate the device. thats why there are so many power pins on the sata power.

now, as to WHY we have so many different types of connections, that goes WAAAAAYYY back to the very early days of pc's and computing. we maintained backwards compatibility (to some extent) with the stuff that was in use back then.

What I am waiting for is the total elimination of the 3.3, 5, -5, -12 volt supplies totally (nearly there with the -5 and -12 being mostly gone now). we have the technology to use a single 12v supply to provide ALL the power withing the pc, by each device doing its OWN regulation down as required by the device. Yes, its gonna take a while for it to happen, but if it does, we can now say hello to power supplies that are more effecient, even able to provide high power outputs without forced air cooling (I used to own a 75A 12v supply that did not have a fan).
November 25, 2008 12:46:42 PM

Quote:
we can now say hello to power supplies that are more effecient,


Yup - but hello to systems that are more inefficient, surely? Right now the 3.3V and 5V power lines can be supplied by secondary windings on the PSU transformer. Forcing each device to regulate 12V down to 3.3/5V is going to be lossy in terms of power and end up with your HDD's / DVD-ROM's getting nice'n toasty.

Good original question though - that 10-to-4 power thing had me puzzled from the start. Personaly would have liked to see data and power combined into one cable from the mainboard too. Also puzzled by the presence of 2-4 floppy disk plugs on most PSU's I fit. Who uses more than 1 floppy drive? Who even uses one floppy drive come to that? Just chop them off and chuck an adapter in the box.

Sorry - getting random. Lunchtime
November 25, 2008 12:58:23 PM

I still use the floppy and Compact Flash drive IDE converters.
You can fit an operating system on a compact flash card and run it more efficiently than if it were on a hard disk. The adapter requires floppy drive power connectors.
Some inexpensive modern power supplies have chopped off the floppy connectors.
November 25, 2008 11:59:46 PM

stuart72 said:
Good original question though - that 10-to-4 power thing had me puzzled from the start. Personaly would have liked to see data and power combined into one cable from the mainboard too. Also puzzled by the presence of 2-4 floppy disk plugs on most PSU's I fit. Who uses more than 1 floppy drive? Who even uses one floppy drive come to that? Just chop them off and chuck an adapter in the box.

Sorry - getting random. Lunchtime


Power and Data on the same cable would have interference implications also, the data has to be shielded from the power for this reason.

And the floppy connectors, i actually use 2 in my system and i dont even have a floppy drive. My X-fi has one onboard and one of the front IO
November 26, 2008 12:02:27 PM

Thanks for the answers.
I understand that you need to convert the voltage carried on the wire so it is compatible with the SATA device, and for this to occur a physically different connection is required.
Why cant this conversion happen inside the actual SATA device though?
If this was made a design standard then in a few years people would only need worry about one type of power (Molex, or w/e you make standard)).

Im sure this would make things like load balancing easier as well.

Thinking about it....i wonder how much revenue the sale of power adaptor units sell for....CONSPIRACY!!!


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