Ok, so I couldn't silence these fans before, because MSI fan control for the SYS_FAN headers goes down to 50% and at that setting the Silverstone AP181 fans spin at around 870rpm, louder than just using the switch on the FT02 case to set them to 700rpm. MSI Command Center in Windows does not allow you very much control either, it's either 50%, 75%, or 100%. No setting in between on the Manual mode. Well, I stumbled on something in the bios, under Monitor you can set the fan speeds, in increments of around 10%! Well, this got me thinking, and I decided to try some things.
First off, I couldn't make the fans silent using the front fan controller, because (this is my first time with one of these) it does not spin up the fans initially like the motherboard does, so if I turn the fans down to silent, they won't spin when the computer turned off and on. So big failure with that. And with the 50% option of fan control on MSI, I couldn't silence them either. Well... I came up with a possible workaround for this.
Set the fans to the low setting with the switch, and connect them to the SYS_FAN headers, so the fans will be getting a lot less than 50% voltage. The fans wont spin at this setting in fact. And they wont even spin hardly at 75% setting using the low setting on the switch, they spin around 380rpm. But because the bios has a 10% increment setting, I was able to set them to 85% or thereabouts. Voila, 530rpm! Now I could set them to around this speed with the manual fan controller, but at 500rpm they wont start spinning after turning the computer off and on. Advantage of using the motherboard headers is that they spin up initially, then turn down to the set speed. At least on this MSI motherboard they do.
So, 530rpm, I can see their rpm's in speedfan, and they are nearly silent now. No more quiet roar going on in the case. All with the AP181 fans.