Power supply connectors

  • Thread starter Thread starter HMSDOC
  • Start date Start date
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HMSDOC

When connecting all the components to the molex connectors from the power
supply, are there any dos and don'ts. For example is it bad using one 'lead'
supplying Molex connectors to power devices that use a lot of juice and are in
frequent use, like multiple hard drives? Is it OK to use multiple connectors
from one lead and none from another?

Howard
 
Or, more simply put, can you just use any Molex connector that you see no
matter what else might be connected on that group of wires, if it is free use
it and don't worry?

Howard
 
HMSDOC said:
Or, more simply put, can you just use any Molex connector that you see no
matter what else might be connected on that group of wires, if it is free use
it and don't worry?

Howard
Click to expand...
If you have multiple HDDs, I like to put seperate connections to them, some
HDDs like the full amount of juice, not to be shared by a Y splitter or the
next connection down the line.
 
Or, more simply put, can you just use any Molex connector that you see no
matter what else might be connected on that group of wires, if it is free use
it and don't worry?
Click to expand...

They are all connected to the same place inside the power supply. I would
not worry about it. I would not connect several of the Y type
adaptors/extenders in series to finally get to a drive.
 
If you have multiple HDDs, I like to put seperate connections to them, some
HDDs like the full amount of juice, not to be shared by a Y splitter or the
next connection down the line.
Click to expand...
Shame that electrically they're all connected to the same point so what
you're doing is pointless.
 
Ralph Mowery said:
free

They are all connected to the same place inside the power supply. I would
not worry about it. I would not connect several of the Y type
adaptors/extenders in series to finally get to a drive.
Click to expand...
I think I rambled a bit there sorry.
I was making the point about not using Y splitters.
 
But I take it from your comments it is OK to use, say, one Y splitter on one
one of the lines, just not Y splitter to another Y splitter? One on a line
should be OK?

Howard
 
But I take it from your comments it is OK to use, say, one Y splitter on
one
one of the lines, just not Y splitter to another Y splitter? One on a line
should be OK?
Click to expand...
It is fine to use one Y splitter. I just would not want to use one after
another but doubt that 2 or 3 in series would make any differance either in
most cases. Most of the power is used by the motherboard in many computers.
The most drives use less power than the motherboard now. It does take more
power to start a hard drive motor than it comsumes after it get up to speed.
 
Whereas On Sat, 25 Oct 2003 22:55:35 +0100, Conor Turton
Shame that electrically they're all connected to the same point so what
you're doing is pointless.
Click to expand...

The point is is they are being fed by different wires.
 
Whereas On Sat, 25 Oct 2003 22:55:35 +0100, Conor Turton


The point is is they are being fed by different wires.
Click to expand...

Haha, that makes no difference. Think about it - if a shorted garbage
disposal overloads the house's circuit breaker, the light in the
refrigerator still goes off even though it's on a "different wire".
 
Conor said:
Shame that electrically they're all connected to the same point so what
you're doing is pointless.
Click to expand...

But if the voltage drop from multiple high current devices makes the LAST
device on the chain get too low of a voltage, problems can and do happen.

PC PSUs are *locally* sensed inside the PSU, so voltage drop in a single
string is not detected. All strings may be +11.985v *at* the PSU, but too
much current through cheap wire/connectors can drop that voltage at the
end of a string to a problem level. If there were no current or resistance
in the string, then your statement would be correct.
 
But I take it from your comments it is OK to use, say, one Y splitter on one
one of the lines, just not Y splitter to another Y splitter? One on a line
should be OK?
Click to expand...
50 on a line should be OK providing the current drawn doesn't exceed
the maximum value for the diameter of the cable core of the original
supply wire.
 
Whereas On Sat, 25 Oct 2003 22:55:35 +0100, Conor Turton


The point is is they are being fed by different wires.
Click to expand...
And the fact is that you're unlikely to exceed the maximum current
capacity for that wire which is the ONLY reason to use more than one
other than for ease of connection. Until you exceed the current
capability of the wire then nothing supply wise will be affected. Also
any noise transmitted on that wire will be reflected on the othes too
so there goes another reason you think you have.

Still, I'll speak as someone who did electronic engineering and you can
keep thinking you know about it just 'case you're capable of plugging a
few cards into a PC. The ability ot build a PC doesn't make you an
electronics engineer.
 
But if the voltage drop from multiple high current devices makes the LAST
device on the chain get too low of a voltage, problems can and do happen.
Click to expand...
Only if you exceed the current capacity of the original supply cable
which is hardly likely to happen on a couple of drives. We're talking
about PC drives...hardly high current devices. Christ, you want to have
seen the current draw on the old RLL/MFM drives back in the 80's.
 
But if the voltage drop from multiple high current devices makes the LAST
device on the chain get too low of a voltage, problems can and do happen.

PC PSUs are *locally* sensed inside the PSU, so voltage drop in a single
string is not detected. All strings may be +11.985v *at* the PSU, but too
much current through cheap wire/connectors can drop that voltage at the
end of a string to a problem level. If there were no current or resistance
in the string, then your statement would be correct.
Click to expand...

Hmmm.... I still spread 8 drives and 2 CDRWs around the power
connectors as well as I can. Had figured that since the string was
supplying all the drives on a parallel basis they would all get the
same voltage but less current....

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Conor said:
Only if you exceed the current capacity of the original supply cable
which is hardly likely to happen on a couple of drives. We're talking
about PC drives...hardly high current devices. Christ, you want to have
seen the current draw on the old RLL/MFM drives back in the 80's.
Click to expand...

*Any* current through the wire results in a voltage drop. This drop is
additive. You make it sound like 4.9 amps, for example, has no drop, but
5.0a suddenly is bad.

Agreed that today's drives don't hog as much current as 5-10 years ago,
but drive start up peak currents are still high, and are affected the most
by cable inductance. PSUs provide multiple strings for a reason. Use them.
 
Overlord said:
Hmmm.... I still spread 8 drives and 2 CDRWs around the power
connectors as well as I can. Had figured that since the string was
supplying all the drives on a parallel basis they would all get the
same voltage but less current....
Click to expand...

*Both* ends of a string must be connected together for it to be considered
a parallel circuit. In PC drive strings, only the PSU side of the strings
are connected together. The device ends are not, thus the voltage drops in
each string can be quite different.
 
Conor said:
50 on a line should be OK providing the current drawn doesn't exceed
the maximum value for the diameter of the cable core of the original
supply wire.
Click to expand...

Oh? And you have developed splitters whose connectors are free of
any voltage drops? Even a slight 10 mV drop per connector would result
in a 1 volt drop on 50 splitters (0.5v drop on the positive side, 0.5v
drop on the common side.)
 
*Any* current through the wire results in a voltage drop. This drop is
additive. You make it sound like 4.9 amps, for example, has no drop, but
5.0a suddenly is bad.
Click to expand...
No it doesn't. I don't make it sound like that at all and if you had
half an ounce of common sense you'd know that.

If you think half an amp is high current then God help you.
 
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