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FRONTPAGE Cooler Master Jetflo Fan Review
- Thread starter Overclockers.com
- Start date
- Joined
- Feb 1, 2011
- Location
- Republic of Texas
Thanks for the review Ed. I should check this out for a project I'm working on. Quiet is good. Seen any price recommendations?
One side note: I think you've mixed your screw size/threads. There's 8-32 and there's 10-24, and then there's 10-32 (fine thread). The 4mm would more closely approximate the #8 screw. Fine thread for a #8 would be 8-36.
One side note: I think you've mixed your screw size/threads. There's 8-32 and there's 10-24, and then there's 10-32 (fine thread). The 4mm would more closely approximate the #8 screw. Fine thread for a #8 would be 8-36.
- Joined
- Jul 29, 2011
- Location
- Buenos Aires, Argentina
I really like how these look, and the design seems pretty smart...
I'd take them for a spin.
I'd take them for a spin.
- Joined
- Dec 16, 2013
- Location
- SoCal
Hey there, chiming in, i was at frys 12/14/13 and saw these, for the price $16.99/ea, i picked up two (120mm) to put on my CM storm side panel. i didnt know they were so new.
Well, imo the power cords are a little short, unless you use the supplied resistor attachments, i left them off, one of them is plugged into a PWM connector, other is straight 3pin fan. im not sure if only one of them spins up or both, but when it does get a load, they can get loud going 2500rpm. fyi.
i do keep my cooling settings on active/aggressive, so idle/no load they are still audible.
Hope this gives some help.
~wolf
Well, imo the power cords are a little short, unless you use the supplied resistor attachments, i left them off, one of them is plugged into a PWM connector, other is straight 3pin fan. im not sure if only one of them spins up or both, but when it does get a load, they can get loud going 2500rpm. fyi.
i do keep my cooling settings on active/aggressive, so idle/no load they are still audible.
Hope this gives some help.
~wolf
- Joined
- Mar 1, 2013
I find it odd that the "silent" adapters don't pass through the PWM signals.
The RPM vs. duty cycle plot looks like a so called "constant torque" motor. It looks like an analog controller, as a digital controller would be smart enough to not allow the motor to stall.
The RPM vs. duty cycle plot looks like a so called "constant torque" motor. It looks like an analog controller, as a digital controller would be smart enough to not allow the motor to stall.
Probably because as a fixed speed reduction by lowering voltage it would not supply 12v to power the PWM PCB in the fan. 
I have wondered about lowering voltage to a PWM fan but have never tried it.
Edit:
I have wondered about lowering voltage to a PWM controlled fan but have never tried it. PWM signal from motherboard and 9-10v instead of 12v power.
I have wondered about lowering voltage to a PWM fan but have never tried it.
Edit:
I have wondered about lowering voltage to a PWM controlled fan but have never tried it. PWM signal from motherboard and 9-10v instead of 12v power.
Last edited:
- Joined
- Jun 17, 2010
- Location
- Marietta, GA
Every PWM fan I'm aware of will do just fine if you control it with voltage, as long as you don't blow the pot that you're using to control it. PWM is kinda an add on, it's not an entirely different system.
- Joined
- Mar 1, 2013
Should work fine as long as the logic still has enough voltage to work. The DSP drive fans even sense the actual supply voltage and account for that in the control algorithm.
BTW, the inner workings of so called "PWM" (variable speed) fans is very different to that of conventional ("fixed speed") fans. While fixed speed fans always use a resolver to sense position and are usually square wave drive, variable speed fans may or may not use resolvers and are almost always sine wave drive. (A notable exception are some higher end "fixed speed" fans that are really variable speed permanently wired for full speed.) Deltas and newer Nidecs use DSP to sense the back EMF, while Sanyo and YS Tech use resolvers.
My best guess is that the Cooler Master is current mode controlled with the PWM input being used to change the excitation voltage of the resolver. (The output amplitude from a resolver is proportional to the excitation voltage, meaning that it works as a crude multiplier.) Not sure what the loop does when there's not enough supply voltage to keep it linear, but they could either let it clip or detect that and turn down the loop gain to compensate. Easy way to check is to reduce the supply voltage, note the RPM and noise (as in if it's buzzy or a smooth hum), then change the supply to 12V and use the PWM input to get about the same RPM before checking noise again.
BTW, the inner workings of so called "PWM" (variable speed) fans is very different to that of conventional ("fixed speed") fans. While fixed speed fans always use a resolver to sense position and are usually square wave drive, variable speed fans may or may not use resolvers and are almost always sine wave drive. (A notable exception are some higher end "fixed speed" fans that are really variable speed permanently wired for full speed.) Deltas and newer Nidecs use DSP to sense the back EMF, while Sanyo and YS Tech use resolvers.
My best guess is that the Cooler Master is current mode controlled with the PWM input being used to change the excitation voltage of the resolver. (The output amplitude from a resolver is proportional to the excitation voltage, meaning that it works as a crude multiplier.) Not sure what the loop does when there's not enough supply voltage to keep it linear, but they could either let it clip or detect that and turn down the loop gain to compensate. Easy way to check is to reduce the supply voltage, note the RPM and noise (as in if it's buzzy or a smooth hum), then change the supply to 12V and use the PWM input to get about the same RPM before checking noise again.
