Motherboard Fan Headers

[mharolde]

Have a couple of questions regarding the fan headers on my Gigabyte GA-MA770-DS3P motherboard. There is a cpu fan header which I am using, no problem there. There is also a fan header for the northbridge. There is a large heatsink on the northbridge and it isn't flat, I have no idea how I would mount a fan on it. Question is, do I need a fan on the northbridge?
Next, there is a 3 pin header for a system fan and a 4 pin header for a system fan. There is also a 3 pin header for a power fan. Question is what is the difference between a system fan and a power fan? My 80mm case fans have 3 pin connectors, not sure I have seen a 4 pin connector for a motherboard header, so how would the 4 pin header be utilized?
Lastly, I read in a thread here that it isn't a good idea to let the motherboard power the case/system fans and I should use the 4 pin molex connectors on my power supply. Is this true? Should I forget about the motherboard fan headers and just use my PSU?
Lot of questions I know, thanks for reading through this and for the advice.

[Midknyte]

power fan is just to sense your PSU fan rpm. System fan is a case fan. 4pin would be PWM aka variable speed.

If you use the molex connectors, the fans will be at 100% all of the time. 3/4pin headers on the MB usually give you some control, especially the PWMs.

[Sterling_Aug]

I prefer NOT to use the mobo headers to power my case fans. I use larger fans and they draw more power than most fan headers are designed to handle. I have blown out several headers over the years so I prefer to use the molex power plugs.

You do not need a fan on the northbridge, but you can install one if you want to.

[Lgbpop]

There are fans and heatsink/fan units designed for the northbridge. Your existing heatsink will have to be removed before you can use another cooling device on it. The way I figure, if your northbridge was designed to use a fan it would have one. A fan may cool more, but the heatsink should be sufficient as designed.

[mharolde]

Thanks for the replies.
Gonna leave the northbridge as it is, the heatsink looks rather robust.
Although I wouldn't mind knowing my PSU fan rpms, it doesn't have a 3 pin connector so I will leave that header alone. I live in a warm climate so I don't mind my fans going at 100%, better to replace fans than computer hardware! So I will use the 4 pin molex connectors for my fans...thanks again for the info.