Daniel said:
Thanks to all who replied,
Will the 20 - 24 pin adapter have any issues I should be aware of, or
do I just attach it?
thanks
Daniel
You don't need that. All that an 20 to 24 pin adapter does,
is more the "burn point" to a different connector. It's a waste
of money and isn't solving a problem.
You can plug a 20 pin into a 24 pin motherboard.
This is how you do it.
http://www.playtool.com/pages/psuconnectors/20in24.jpg
( from
http://www.playtool.com/pages/psuconnectors/connectors.html )
To discuss the topic of the ATX power connector, the first concept
is "ampacity". That is the room to move amperes of current through
a wire and connector pin. Usually the wire is thick enough, to not
be the limiting element. That means the discussion will focus on the
pins on the main ATX connector.
The ATX main connector pins can carry about 6 amps each. This table
is copied from the playtool.com site as well. I've placed a space
between the 20 pin section and the extra pins used for the 24 pin
connector.
Description Color Pin Pin Color Description
+3.3 volts orange 1 13 orange +3.3 volts
+3.3 volts orange 2 14 blue -12 volts
ground black 3 15 black ground
+5 volts red 4 16 green PS_ON#
ground black 5 17 black ground
+5 volts red 6 18 black ground
ground black 7 19 black ground
PWR_OK gray 8 20 white -5 volts (optional, may be missing)
+5VSB purple 9 21 red +5 volts
+12 volts yellow 10 22 red +5 volts
+12 volts yellow 11 23 red +5 volts
+3.3 volts orange 12 24 black ground
On the 20 pin section, there are four red wires carrying +5V.
Four wires at 6 amps each, is room for 5V @ 24A to flow. Adding
an extra 5V wire increases the room to flow to 5V @ 30A. But
on modern systems this is overkill. It would be a strange
design that even reached 20A on a modern board. (The exception
to this rule, is the older S462 boards which powered the processor
from +5V. If the processor isn't drawing power here, the load
will be a lot less.)
On the 20 pin section, there are three orange wires, making
room for 3.3V @ 18A to flow. The same logic applies in this
case. The extra pin on the 24 pin section does increase
the room to 24A, but the load isn't going to be that great.
I think my P4C800-E uses 14A or so, using linear regulators
running off that rail for things like the chipset and DIMMs.
The last one to consider, is the 12V, and this one is more
important. The main 20 pin has a single yellow wire. That
is room for 12V @ 6A to power the motherboard. If the
wire on the 24 pin section was available, the current
carrying room would increase to 12V @ 12A.
The fans draw power from that rail. You might allocate 0.5A
for fans connected to the three and four pin fan headers.
Your PCI Express video card may draw power from that slot.
Consider a couple test cases.
A 6600GT draws perhaps 4 amps from the PCI Express slot, on
the 12V pins. If you had only one video card, the 20 pin
connector has sufficient current carrying capacity to handle
it.
If you had an SLI motherboard, with two PCI Express slots,
and installed two 6600GT cards, now the load is 8 amps. That
is 2 amps above the conservative limit of the 20 pin connector.
A 24 pin connector with its 12A ampacity, handles that with
margin to spare.
Some motherboards placed a Molex 1x4 connector near the two
video card slots of an SLI board. That Molex can handle perhaps
8 amps. The 6 amps of a 20 pin connector plus 8 amps on the
Molex if plugged in, would have given room for 14 amps total.
So again, two video cards could be handled. Modern motherboards
have stopped including that optional Molex 1x4, so it is less
available now.
On some of the more modern PCI Express video cards, the situation
is shifting a bit. The slot power is actually dropping, while
the majority of power comes from the PCI Express 2x3 or 2x4
connectors on the end of the card. You could plug two of
those kind of video cards into the motherboard, without
needing a 24 pin power supply. I've only seen one exception
to this - I saw a low end Nvidia card the other day, where
the bumpkins got rid of the PCI Express connector on the
end of the card - that forces all the current to come
from the slot. Their competitors continue to use the PCI
Express 2x3 connector, which is safer for spreading the load.
*******
The above addresses the "room for current to flow". The purpose
of that, is to prevent any connector pins from getting burned
or the surface plating from being damaged by oxidation.
The ability of the power supply to deliver the current is
also very important. Say you had room for 20A to flow, but
the power supply rating was only 15A. Then you could never
burn the connector, because any attempt to draw more than
the 15A, results in the PSU turning off on "overcurrent".
The end result is, we have two questions to ask, before
deciding whether the Enlight GPS-350BB-104 is the right
supply for the job.
1) Do you have two PCI Express video cards ? If you have
only one video card, chances are the single 6 amp
wire, can handle a 4 amp video card plus 0.5 amps of
fan headers.
2) What power does your PC draw ? High end video cards make
a big difference to this calculation. You'd have to
give a hardware inventory of everything in the PC,
to estimate the power. In addition, you'd have to
read all the numbers off the label of the supply. Every
number on the label means something. If the Enlight 350W
doesn't have sufficient power, then you buy another supply.
My current Core2 PC could easily run from a 350W supply.
I use a 65W processor, and the measured power consumption
with Prime95 running is only 36 watts. My video card is
maybe 45W or so. The 65W would come from the 12V rail, so
that would be a bit more than 12V @ 5A and that would
flow through the ATX12V 2x2 square connector. So I wouldn't
have a problem using the 350W.
On paper, your Enlight is a pretty flexible supply. There
is the letter C on the end of this part number, and perhaps
you have a different version than this. GPS-350BB-104C
http://ep.yimg.com/ca/I/yhst-90432262887525_2079_112692772
5V @ 30A 3.3V @ 28A 12V @ 18A -12V @ 0.8A -5V @ 0.3A +5VSB @ 2A
<--- 210 watt max -->
<---------- 340 watt max -------> <--- no more than --> <-- 10 watt max -->
0.8A total current
That makes it closer to a 360W supply, if you believe the bottom line
limitations are to be applied simultaneously.
The supply is flexible, because the three main rails have high
current limits. You could run an older system with a heavy
+5V loading pattern. Or run a modern system with a heavy
12V loading pattern. Usually, one of the three rails is
dominant in terms of loading, and the other two aren't
near their limits.
So with your more modern system, you have to work out your
12V amperage, and also work out your total system power.
And for that, a complete hardware inventory is required.
If you have a low end system like mine, it would run
on that supply with no problem.
Paul
