3 pin fans do in fact have speed control from the BIOS. I am running 15 of them off the non PWM Chassis headers with speeds of 325 to 1240 rpm.
Your MoBo will have one or two CPU headers....these are always PWM and will work with BIOS control or MoBo software ....or Speedfan on many boards.
Your MoBo will also have a number of CHA headers .... these may be 3 or 4 pin. Regardless of popular rumor, 4 pin does NOT mean they are PWM..... I have seen MoBo manuals actually say that they are but a call to TS has always confirmed that they are not. I have not as yet seen a MoBo that actually uses PWM on a chassis header. You can run 4 pin or 3 pin fans off these headers but they will use VV (variable voltage) control rather than PWM.
Options....
PWM-1 - If ya have two CPU headers, run the cooler off the 1st and ya case fans off the other. Make sure to limit ya amperage to the header rating and include start up current....for example:
I'll use up to two 0.33 amp 1800 rpm fans on 1 amp header (67%)
I'll use up to two 0.41 amp 1200 rpm fans on 1 amp header (83%)
You can get more fans off this header using a Fan PCB like the one here:
http://www.frozencpu.com/products/20988/ele-1196/Swiftech_8-Way_PWM_Cable_Splitter_-_SATA_Power_8W-PWM-SPL-ST.html
This has a 12v molex connection and ya can have 8 fans off single header..... you will need PWM fans tho.
PWM-2 - Phanteks has a similar PCB that is pure genius .... it works as above except that ya can use VV 3 pin fans. It comes with all the Phanteks cases but you should be able toi order one as an accessory by the end of the month.
VV - Again same as above but if ya add the 12V Molex, ya fans run at full speed..... the Phanteks PCB works just fine like this.....At 1200 rpm, ya can go up to 6 Phanteks 140mm 1200 rpm fans with reasonable margin of safety (6 x 0.14 amps = 0.84 amps.). I have 3 of these as follows all working off my variable voltage chassis headers with 3 pin fans:
CHA_1 => PCB-1 => (5) case Fans
CHA_2 => PCB-2 => (4) fans on UT60-280 Radiator
CHA_1 => PCB-1 => (6) fans on XT45-420 Radiator
All are controlled (325 - 1240 rpm) via the BIOS with the Asus FanXpert2 software serving as the interface between me and the BIOS. Can also choose several different options in the BIOS based upon a list of available profiles. I actually forgot that two of the case fanms were provided on splitter cables so at one time I had 8 connected and nuthin blew up.... but as they never break 850 rpm, that's really not that surprising.
ModMyToys has several other VV PCBs is ya don't wanna wait for the Phanteks.
http://www.frozencpu.com/cat/l3/g/c121/s424/list/p1/b214/ModMyToys-Fan_Accessories-Multi_Fan_Ports-Page1.html
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