http://www.alliedelec.com/search/productdetail.aspx?SKU=70226025#tab=specs
They were only 2W 3000RPM 51CFM 34dBA Sunons on my last Hex16B.
Seriously these fans are dangerous at 4500RPM without a guard. Watch out for your fingers! Noisy as hell too.
UPDATE: Just set all the 4500RPM fans to 5v. They probably still do 1875 RPM 31CFM. Seem to be keeping things cool enough for now.
Got some Arctic F9 on order, just the regular 1800RPM 43CFM ones without temp control, cheap as chips.
Ok, now i feel so stupid looking for replacement Fan.
The SUNON Maglev PF92251V1-000U-S99 is PWM fan, so what i need is to build PWM fan controller.
Did you choose this fan? I noticed the PWM blue/yellow wires were chopped off to make it non-PWM
It would probably be best to run them at 7v by plugging the ground into the 5v (+12V-+5V=7V), then it should be 2625RPM 43.75CFM, but I'm not sure how the board or other peoples PSU will handle it. Soldering in a resistor on the 12v line, or even better a variable resister with 3 settings for 12v-overclocker,7v-normal,5v-underclocked, probably the safest option.
The Arctic F9 (AFACO-09000-GBA01) non-PWM non-temp control fan is good combination of airflow/quiet/price/safety.