I was having difficulty with booting my new system, so I replaced the power supply with a new Antec TruePower that is actually P4 compliant. I have an Asus P4S533, and I notice that its AUX power connector is 4-pin, just like a peripheral power connector.
The AUX power lead from the power supply is a 6-pin connector. I also have a feeling that plugging in a peripheral power lead to the AUX connection on the motherboard is not right.
So, I don't have the AUX power connected. The system works fine, I'm not really worried, but I am curious as to why the connectors don't match, or what the effect of having it plugged in is. Any experience?
Antec's own web site calls them P4 compatible so you don't have to worry about that. They all use a 6 pin AUX connector. Although they don't have a pinout picture, it appears that there are two extra ground connectors. You can check with support as to its function. Usually it is for a themal cut out if the PC reaches overload.
I have the plain jane antec P/S which comes with a case and also a P4S533 although they aren't together. The antec P/S should have the 4 pin square connector that P4's use and I assume you plugged that in as well as the 20 pin ATX power. The P4S533 have in addition to those a 4 pin horizontal power input. I found a lead off the P/S which didn't have the little floppy power plugs and plugged that in. I assumed it might be power for chassis fans. The 6 pin horizontal power lead is in all my atx P/S and goes unconnected.
It has TWO auxilary power connections, the first is between the CPU socket and the printer port, and is square, it is a standard P4 auxilary connector. The other one, located next to the ATX power header, is a standard drive power connector. The second one is there for use by people who don't have a "P4 compatable" power supply, i.e. don't have the 4-pin square one. It's a substitute.
<font color=blue>At least half of all problems are caused by an insufficient power supply!</font color=blue>