newbie Q - Power Supply cables

  • Thread starter Thread starter Gilgamesh
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Gilgamesh

I'm not really a newbie but I don't know a lot about power supplies.

Is it possible just to have all my devices running off one long daisy chain
of molex Y adaptors as a means of hiding my cables thus improving air flow.

A potential problem I see with this is that the current draw along the
original power supply output cable may be such that there won't be enough
power supplied for everything. (I'm assuming that the interior of the power
supply has independent means of supplying power to each output cable, if it
doesn't then the question is moot).

Thanks
 
Gilgamesh said:
I'm not really a newbie but I don't know a lot about power supplies.

Is it possible just to have all my devices running off one long daisy chain
of molex Y adaptors as a means of hiding my cables thus improving air flow.

A potential problem I see with this is that the current draw along the
original power supply output cable may be such that there won't be enough
power supplied for everything. (I'm assuming that the interior of the power
supply has independent means of supplying power to each output cable, if it
doesn't then the question is moot).
Click to expand...

All wires of the same voltage go to the same point inside the power supply.
You can run into problems by using one long daisy chain due to the voltage
drop along the wire and connectors if you use multible Y connectors. The
wires going to the connectors are usuallt too small to power more than 2 or
3 devices each. YOu could go inside the supply and bring out larger wires.
 
I'm not really a newbie but I don't know a lot about power supplies.

Is it possible just to have all my devices running off one long daisy chain
of molex Y adaptors as a means of hiding my cables thus improving air flow.

A potential problem I see with this is that the current draw along the
original power supply output cable may be such that there won't be enough
power supplied for everything. (I'm assuming that the interior of the power
supply has independent means of supplying power to each output cable, if it
doesn't then the question is moot).

Thanks
Click to expand...

To a limited extent you could get away with it. A decent
power supply, with 18 gauge (printed on side of wire
insulation) should easily be able to power two hard drives,
an optical and a fan or two, but there's not really any
reason to try pushing it. I mean, there is very little
difference in airflow from having a power cable running
through the system, or two, or four. If the space is that
tight it would seem you won't have good cooling regardless
of an extra cable lead being there or not.

Don't be fooled by kids that claim it's important to get
every tiny thing out of the way of airflow, air is not like
light, the pressure difference will cause flow around
obstacles just fine, providing a hot part is not immediately
behind a very large obstacle like a ribbon IDE cable.
Ribbon cables don't really need much care in routing to keep
drives cool either, as the air travels the whole length of
the drive before being diverted in the typical case
arrangement. A degree or two difference isn't significant,
room temp and system load fluctuations accound for more than
that.

In summary, it'd be better to just use the typical cable
arranagment, if the system is too hot then there are more
basic things needing done which will have enough impact that
a very minor cable won't matter.
 
Ralph Mowery said:
All wires of the same voltage go to the same point inside the power
supply.
You can run into problems by using one long daisy chain due to the voltage
drop along the wire and connectors if you use multible Y connectors. The
wires going to the connectors are usuallt too small to power more than 2
or
3 devices each. YOu could go inside the supply and bring out larger
wires.
Click to expand...

The voltage drop sounds like what i was worried about.
My power supply is 550W and has 4 molex cables coming out of it.
I need to power DVD & floppy drives, nine hard disks (7 SATA, 2 PATA),
graphics card, and six fans.
Going down the reverse path of my original post and looking at more cables
could I add extra molex outputs from my power supply to drive everything and
avoif the voltage drop.
 
The voltage drop sounds like what i was worried about.
My power supply is 550W and has 4 molex cables coming out of it.
I need to power DVD & floppy drives, nine hard disks (7 SATA, 2 PATA),
graphics card, and six fans.
Going down the reverse path of my original post and looking at more cables
could I add extra molex outputs from my power supply to drive everything and
avoif the voltage drop.
Click to expand...

Adding more outputs from the power supply is generally a
pain in the ass. It's not that its' hard, but tedious.
Larger power supplies generally don't have but one, if any,
unused spots on the PCB for additional power leads. With
with several leads already is going to take a heavy-duty
soldering iron and complete disassembly to pull wires out,
keep molten solder under control, and attach new leads.
Delicate, precision work is easier, IMO.

What you could do is get some heavy, low-gauge straned 3
conductor wire, perhaps 10-12 gauge. Run one lead for 12V,
5V, and Gnd, down to a distribution block lower in the
system, to which you attach the leads you removed from the
PCB to make room for the three 10-12 gauge leads. IMO, it
is not necessary to do this, as I already posted the impact
on airflow should not be bad when putting a couple or three
drives per lead. As for the fans, it may help to have a fan
bus or some extensions and wire managment (like stick-on
clips or cable ties).
 
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