The stock cooler is PWM I think which means that if you have the correct settings in your motherboard BIOS, the fan should only spin fast enough to keep the processor cool (between safe temperatures). It will then spin faster as required.
A RPM of 2000 seems very high as the i3s are very cool processors and require a fan speed of only around 1000rpm under load in my experience. Your system will be louder with a fan on 2000rpm so you can let your motherboard control the fan speed if you wish.
BIOS settings are usually something like:
AUTO, PWM and Voltage
Get a CPU stress test program (google) and see if you hear a CPU fan speed change (should be very obvious). If it doesn't change under stress then it's already at 100%. In that case, you need to try each setting. It's either PWM or Voltage (Auto just guesses). If it's on PWM then choose Voltage on vice versa.
You can buy non-stock HSF's with 120mm fan (good ones are $40), but only get one of your CPU fan is changing speed and it's still too loud for you.