Controlling case fans

[varblane]

I have Thermaltake Armor jr. case with 2 fans(1 in the front and 1 in the back)
Motherboard is Gigabyte p35-ds3r and it is powered by chieftech 620W PSU.
The problem is next.. it should be controlling itself the rmps, but after some while of working when the components get little warmer the fans go on 1300rpm or so. the problem is that its noisy. I'd like to turn it to 800. it cannot be controlled by the SpeedFan. Can i change it in Bios and if yes then what should i do there.

Fans are connected to the PSu(there is some case fan wire) and the sensor or whatever cable comes from the PSu.
my english isnt good and i hope you can understand and help me out with my problem.

[Spawne32]

Im curious to know which case fans your talking about in an armor jr., because the only fans the armor jr. comes with are standard TT fans with only 4 pin molex connectors, there is no RPM monitor and no way that speedfan can even detect the fan speed because there is no wire for the motherboard header.

[varblane]

the fans are connected to the 4pin connectors which is meant for Case Fans.. And a wire comes from Psu ( Chieftech 620W) To the Sys_fan.

[i43]

I think You need to replace default fans with such ones what can be plugged mounted to MoBo ( 3 pin ) Fan connectors, then you can use software
to ( speedFan 4.xx) or may be some other to adjust their speeds , also if plug them to right pins ( check your mobo manual ) they can be controlled via BIOS
Hardware monitoring utility.
Other ways You need an extra fan controller but still need some re-wire works with fan connectors, (4 pin molex must be replaced) because most fan-controllers use (similar to MoBo) 3 pin connectors

sample pic: fan with 3 pin connoctor