I am not knocking the cutting up of the stock fan but if it does not work well you no longer have the stock fan.
I got the deltas on ebay for 41 bucks a total of 5 of them that is 8 bucks each . 2 per s-5 a 16 dollar mod.
But I had proper power supply to act as a controller.
Any psu that has the adjusting range of 5 to 10 volts would be a great controller for the delta's.
http://www.ebay.com/itm/Switching-Power-Supplies-100-8W-9V-11-2A-Power-Supply-/171616908246?pt=LH_DefaultDomain_0&hash=item27f52a33d6or this one this centers at 7.5 volts
http://www.trcelectronics.com/View/Mean-Well/SE-100-7.5.shtmlthis one centers at 9 volts
http://www.trcelectronics.com/View/Mean-Well/SE-100-9.shtmlboth of the ones above could control 8 fans . get the 7.5 if you want quiet and underclock
get the 9 volt one if you want to run a little louder and overclock.
they are lowe cost cheaper then a fan controller and they run more fans.
or you could use the one I had which costs a little more ,but has full range for the fan speed
the delta's allow me to do freq 393 and 1292 -1300 gh hash using 9.2 volts in a push pull sound level = 60-62db
the delta's allow me to do freq 300 and 990-1000 gh hash using 5.5 volts in a push pull sound level = 47.7 to 49 db pretty quiet
in my setup I am opting for the lower freq as sound is an issue
I will see how well it does in the morning