CNPS10X add-on fan
Im looking at the Zalman CNPS10X Flex heatsink and I see that I need a 120mm fan. Can I add any old case fan or do I need a fan specific to this heatsink?
You can add the same fan if you are satisfied with its airflow and noise. If it has a 3 pin connector you can connect it to the mobo and have the mobo controlling the RPM (better), if it has 4 pin molex, then you must connect it to the PSU directly, but it'll run at full speed.
If you can afford to buy a new fan I recommend this one:
Scythe Slip Stream 120mm x 25mm PWM Fan - (SY1225SL12LM-P) 11$
It has PWM control and excellent airflow to noise ratio.