Ken Palmateer said:
Hey Folks:
Can anyone tell me the importance (if any) of the various
versions of the power supplies, eg 1.3 or version 2? I will be using
an Asus SLI motherboard with socket 939. Does it matter if I get a
PSU with 1.3, for instance? Ken
The differences in ATX power supplies that come to mind:
1) Initial ATX had 20 pins and no 12V processor power connector.
May have also had a 1x6 connector, that had extra 3.3V amongst
other things on it. Perhaps that was added slightly later than
the initial 20 pin output ?
2) Added the 2x2 square 12V connector for P4 boards (and later
some AthlonXP and Athlon64 boards).
3) Changed connector to 24 pins, to help with powering PCI
Express slots. Removed -5V due to it being obsolete and
not really necessary on a motherboard. Pin is replaced
by "reserved", so nothing gets burnt. Split the 12V output
into 12V1 and 12V2, which was done to meet the requirement
that no output have more than X watts of power on the output
(some kind of fire safety requirement?). One of those outputs
is used for the 2x2 processor connector, and the other output
supplies motherboard and peripheral 12V requirements.
(Note: Motherboard voltage monitor, only monitors one of
the two 12V signals. The other is unmonitored.)
You can use just a 20 pin connector, provided the PCI Express
video card(s) plus the fan headers on the motherboard use
no more than 6 amps. That basically means one video card plus
fans (as the worst video card I can find data for, is 4 amps
on +12V).
By plugging in the EZplug molex connector, the room for current
to flow increases to 6+8=14 amps. Which is enough for two video
cards.
Alternately, if using a 24 pin main connector, which has two
12V pins on it, the room for +12V currents to flow is 6+6=12amps.
Using the EZplug in this situation, is beneficial due to the
close proximity of the EZplug to the two video cards.
So, from a wiring perspective, if you use one video card, virtually
any wiring configuration will work, and more wires are better.
And once the wiring requirements have been met, the current output
rating on the label on the side of the supply, has to be sufficient
to meet the requirements of the load. You can get estimates for
the current needed here:
http://takaman.jp/D/?english
The tool will give a total +12V current needed, and if using an
ATX supply with 12V1/12V2 split output, you need to split the
results from the Takaman web page, into a processor only number,
and a number for the remaining current.
In terms of the various standards, I'd like to be more precise
about the evolution of the standards, but the formfactors.org
web site doesn't keep all the old versions in their download
table, and their document file naming scheme is nuts.
HTH,
Paul
