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RE: Some additional thoughts on a separate set of PSU's for your cMP... (Of course, long!)

Daniele

Welcome. I hope it helps.

With 5 Sigma regulators, I'd suggest using them for the following voltages:

ATX-20 3.3v, 5v, 12v (3 Sigmas)

P4 12v (1 Sigma)

HDD/USB 5v (1 Sigma)

My reason for picking these voltages is that these are ones that will have a high amount of noise fed back to the regulator and the Sigma should do a pretty good job of dealing with this noise.

If you use separate supplies for the 5vSB & PWR_ON and for the 5v USB, no reason to use Sigmas, just go with LT1085/LT1083/LT317/LM317-type regulators.

I suspect, but do not have evidence, that it will sound better to have a separate power supply feeding the 5V USB than to use the same one for both the HDD and USB. But it's easier to start with just one and add another later.

As for where to connect the negative wires from each Sigma, this would be to the ground wire of the corresponding power connector. Let me revise what I said above to try and make it clearer:

ATX-20 5v - Two sets of 4 wires coming from the 5v regulator. One set is made up of a pair of wires taking the 5v positive to ATX-20 connector pins 19 & 20 and these are braided 4-cross with a pair of wires taking the 5v ground/negative to the ATX-20 connector pins 16 & 17. The other set is made up of a pair of wires taking the 5v positive to ATX-20 connector pins 4 & 6 and these are braided 4-cross with a pair of wires taking the 5v ground/negative to the ATX-20 connector pins 5 & 15. While both of these sets connect to the specified various pins on the ATX-20 connector at the motherboard, they all come together and are connected in parallel at the 5v regulator output at either the 5v positive or negative connections.

ATX-20 12v - One twisted pair of wires coming from the 12v regulator, made up of a 12v positive wire from the regulator to ATX-20 connector pin 10 twisted with a ground/negative wire from the regulator to ATX-20 connector pin 7.

ATX-20 3.3v - One twisted pair of wires coming from the 3.3v regulator, made up of a 3.3v positive wire from the regulator to ATX-20 connector pins 1, 2, & 11 (all tied together at the connector) twisted with a ground/negative wire from the regulator to ATX-20 connector pin 3

P4 12v - One set of 4 wires coming from the 12v regulator, made up of a pair of wires taking the 5v regulator's positive to the P4 positive (yellow) wires and these are braided 4-cross with a pair of wires taking the 5v regulator's ground/negative to the P4 ground (black) wires.

I really need to draw a picture... Sorry, I'm generally very bad about that. I'll see what I can do and post this week. I can also post instructions for making the 4-cross braids, if you need that.
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  • RE: Some additional thoughts on a separate set of PSU's for your cMP... (Of course, long!) - GStew 07:09:03 12/13/10 (0)
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