In article ,
"Michael W. Ryder" wrote:

snip

Is the extra 12V connection on the 24 pin connector only used for PCI
Express? The reason I ask is that I have a P5P800 which has the 24 pin
ATX connector but does not have an PCI Express slots. I got a power
supply with the right connector but wonder if I needed to.



I haven't a clue why they did that. It doesn't make much sense,
because as a rule, the only load on the main ATX power connector
is the fan headers, for the single +12V signal. The 2x2 connector
supplies the heavy processor Vcore current via two of the four
pins (the other two pins are ground returns).

Adding a second +12V pin via the 24 pin version of the connector
just doesn't add up. Neither do the other extra pins (3,5,gnd listed
in the manual) appear to be necessary, as the existing +3.3V
and +5V pins were already enough for the job. This is, after all,
a P4P800 board, with a LGA775 processor socket, so power requirements
should be very similar to the P4P800. Hope I'm not missing something
obvious there...

Maybe the marketing department wanted all the P5xxxx boards to
be the same :-)

Paul