John McGaw wrote:

" 20 + 4 = 24, or so the manufacturer suggests. It appears that you are
expected to use the standard 20-pin cable plus the 4-pin "P4" connector
to do the job. "


I'd like to see you try that one.

A few years ago motherboards only needed a 20-pin connector. The 4-pin
12V connector then became necessary for the Pentium 4. AMD eventually
caught up with its use of the 4-pin connector, yet it is still often
known today as a "P4 connector". Then, with the introduction of
PCI-Express chipsets, motherboards began to need separation of the 12V
rails through the main connector, so a 24-pin connector was introduced
to replace the 20-pin one.

You will often see PSUs advertised as having a 20-pin and a 4-pin
connector, which usually means a 20-pin main connector and a 4-pin 12V
"P4" connector. You also see some advertised as having a 20+4-pin
connector. You can't take the 4-pin "P4" connector and fill up the
missing slots on a 24-pin socket. Not only will it not fit (unless
considerably forced), but you will invariably need to plug in the 4-pin
connector elsewhere on the motherboard anywhere.

When you see a PSU advertised as 20+4-pin, it usually means that it has
a snap-away connector for use with either a 20-pin or a 24-pin main
socket. The 4-pin part here is not the same as the 4-pin "P4"
connector. You can see one of these 20+4-pin connectors he
http://www.highpowersupply.com/icon/20+4main2.jpg

This quide from November 2005 explains it all a bit further, but came
before the introduction of the new 8-pin 12V connector.
http://tomshardware.co.uk/2005/11/23...uk/page19.html

Most motherboards will soon move on from the 4-pin 12V connector to the
new 8-pin 12V connector. Like many new motherboards, this Gigabyte
GA-965P-DQ6 will need both a 24-pin main connector and an 8-pin 12V
connector. http://www.hexus.net/content/item.php?item=6233&page=4

You can get 20-to-24-pin adapters and 4-to-8-pin adapters, but there is
no guarantee that either will be able to supply a stable draw along the
new rail splits.
http://www.newegg.com/Product/Produc...82E16812183045 Some
motherboards don't like them, so you are invariably better off with a
PSU that handles the relevant splits itself.