Re: PSU versions

"" <cyber@xxxxxxxxxxxx> wrote in message
> Hi,
> Any Ideal since went (or what type of monther board) do not
> required -5V.
> I have a old P3 600Mhz. Recently I replace with new power supply, also
> notice the -5V pin is no more there. It works fine.
The general 'need' for -5, disappeared very early indeed (it went with the
switch from socketted 'chip' memory, to SIPP/SIMM memory). However
(unfortunately), many motherboards, still 'check' for the rail, and in a
few cases, used it for odd other things. The ATX 'specs', dropped the
requirement for the rail over 3 years ago, yet a few boards even today,
'want' it...

> "Paul" <nospam@xxxxxxxxxx> wrote in message
> news:nospam-1911051817230001@xxxxxxxxxxxxxxxx
>> In article <alqun151stkv37fiqc3hhe81upm7gei8u5@xxxxxxx>, Ken Palmateer
>> <kenpalmateer@xxxxxxxxxxxx> wrote:
>>> 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 ?
I think it predated ATX. On the old motherboards, using the SIL power
connector (original IBM AT etc.), this connector was added for 'server'
boards, and the early ATX supplies, usually offered the SIL connector, as
well as the ATX connector, including this extra plug, which carried on
being used on the server machines.

>> 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:
>> 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
>> web site doesn't keep all the old versions in their download
>> table, and their document file naming scheme is nuts.
>> HTH,
>> Paul

Best Wishes