25 degrees is a nice low case temp. That is probably why the motherboard CHA_FAN 1& 2 don't turn ON. I like to see the front fan, top, and the rear fan run at full speed and I suggest that you connect these fans directly to the PSU using Molex connectors daisy-chained as you suggested. Leave out the Y-adapter because I read elsewhere about some product issues on this (may be ok now).http://www.newegg.com/Product/Product.aspx?Item=N82E16812201009&cm_re=fan_cables-_-12-201-009-_-Product
Try your local computer store too, for the Molex fan cables (daisy-chaining type).