Can somebody help me with PWM fans? I've bought 2 Thermalright TY 143s for my S5. When I plug one into the 2nd fan header it spins up to 1200RPM and stays there. As far as I can tell the pinouts are standard:

Pin	Use	Wire (new)	Wire (stock)
1	GND	Black	Black
2	+12v	Yellow	Red
3	Sense	Green	White
4	Control	Blue	Blue

Why won't my fan do more than 1200RPM? What I want to do is replace the stock fan with both 143s (push-pull) but they won't do the job at this speed.