Harry said:
On 10 Feb 2005 17:17:28 -0500,
(e-mail address removed)-spam.invalid (claeyss) wrote:
My A8NSLI deluxe uses a 24 pin ATX connector. You need to get a 20pin
to 24 pin adaptor. It is a good idea also to replace the PS with one
with higher wattage output. I am running a Thermaltake 480 watt in
mine. 2 x SATA (RAID), 1 x ATA hard drive, 2 DVD writers, floppy
1x 6600 GT video card (can't afford 2nd yet) and 1 gig Corsair ram
(512 x 2 matched pair)
Using a 24 pin power plug is not absolutely essential. Of the
extra four pins, one pin is a +12V pin, and it is used to supply
power to the video card(s). The A8N-SLI also has the EZplug, which
is a disk drive power plug that feeds the video card(s). Between
the one +12V pin present on the 20 pin portion of the power
connector, and the one +12V pin present on the EZplug, that can
pass up to 6+8amps = 14 amps to the two video cards. That is
plenty to power two video cards.
From some Asus promotional material:
"Unlike the SLI solutions by other manufacturers, the
EZ Plug supports the 20-pin standard, which is still
currently the mainstream. Users who want to upgrade
to the latest SLI platform, can save the extra cost on
a 24-pin power plug."
Are the fans spinning after you press the power button ?
That means the PSU is getting the signal to start (PS_ON#).
In this case, you need to connect three power connectors.
The 20 pin ATX main cable, the 2x2 square +12V (processor
power), and the EZPlug (video card power assist).
This is how the powering works, based on what I've read.
What I don't know, is if the EZplug comes with an interlock,
to prevent the board from powering up if the red LED is lit.
ATX 2x2 +12V ------------> Two power pins to ... Athlon64
------------> Vcore (16amps max) Processor
(24th pin +12V wire) ------6amps max----+---+---VideoCard1
| | (approx 5amps)
(20th pin +12V wire) ------6amps max----+ +---VideoCard2
| | (approx 5amps)
(EZplug +12V wire) ------8amps max ---+ +---Fans
(approx 1amp)
If you use a 24 pin power connector, you have room to push
12 amps right there. Enough for the load shown on the right
of the diagram. But the Asus marketing material claims the
shorter path from the EZPlug to the video cards helps. Inserting
the 24 pin plus the EZPlug can only help.
If you use a 20 pin power connector plus the EZPlug, you have
room to push 14 amps (and the big "if" here, is whether an
old power supply with a 20 pin connector, could actually be
big enough to supply 20 amps or more for the total load in
the computer). The manual has a section detailing total load,
and it recommends some total amps on output for various configs.
So, the combinations one more time:
24pin + 2x2 processor power (theoretically enough)
24pin + 2x2 processor power + EZplug (improved stability)
20pin + 2x2 processor power + EZplug (good working combo)
If you have a single low end PCI Express video card, you could
try the following. Since the 20 pin ATX power only passes
6 amps via one wire, you will need to find a review of your
PCI Express video card on Xbitlabs, to find out exactly how
much your card draws. The fans draw some current, leaving
about 5 amps for your single low end graphics card.
20pin + 2x2 processor power (lower end graphics only
or at least be careful to
research your total load)
As for the PCI Express standard, I don't actually know what
the amperage limit is for the video card edge connector. I
think PCI Express has an overall 75 watt power limit for the
slot, and that power will be split over the +3.3, +5, +12V
and so on power pins on the edge connector. I think there was
an article that stated the number of pins and how many amps
each (like an amp per pin on the edge card), but cannot find
it right now.
HTH,
Paul
