How much power wasted?

[ballzley]

I'm building a new set-up, with a new case (Phantom from NZXT), and I'm shopping for case fans to go with it - specifically about 120mm case fans. I'm looking to get at least four 120mm fans.

I'm digging the Gentle Typhoons a lot, but the models I initially wanted (ap-15, ap-45s) are not PWM. I wondered how PWM (4 pin) could be superior to non-PWM (3 pin), and found this thread: http://www.overclock.net/t/989566/pwm-fans-what-does-it-mean

And a poster claimed that not only will PWM allow the motherboard to control the fan speed (given that it's plugged into the proper PWM fan slot) based on temperatures, but it would also conserve power when not needed/not under much load; whereas with a non-PWM fan (standard 3 pin) will either run at 100% all the time, or have to be downvolted via a fan controller - wasting the "subtracted" voltage as some sort of thermal respiration. Correct me if anything is false/misleading so far.

Before I ask the burning question (see thread title), I am now considering the higher RPM Gentle Typhoon models (AP-29 specifically) that have the PWM capability after a bit of soldering... but they are about $8 more expensive each. They also look rather cheap, but I will be dyeing/painting the fans anyway.

So then I ask: how much power is wasted using those non-PWM fans, and will I be indeed saving power by using the modded PWM-capable Gentle Typhoons (also after the fact that they are ~$8 more expensive each)? I will be using these for at least a few years, almost every day.

Thanks for reading

 

[DragonChase]

You can buy splitters/extensions that will reduce the power of the fans. But if you are worried about fans i highly recommend a fan controller. My case has for example 2 buttons that let me decide how fast it should go, you can buy such a module seperately. In my case, one button controls loop A and second button controls Loop B.

Example Loop A: Front fan, side-panel fans.
Example Loop B: Top back fan, Top fan.

Is this what you are looking for? when im rendering massively i put everything on max and when i decide to chill out or game i reduce it massively reducing noise to next to nothing. When im mining litecoin and i am at work, i just put it on max in a cold room.

Have i helped you in anyway?

 

[Someone Somewhere]

As far as the power issue goes, a PWM and non-PWM fan on full will use about the same amount of power (assuming same fan size, type etc.), but a PWM fan on midway will use less than a non-PWM fan.

Resistoring a fan down will save some power, and some will be converted into heat in the resistors. Still a net saving, but less so.

The other option is to run the fans at 7/5V, which avoids the whole mess.

The amount of energy saved is ridiculously small though. At most a dollar a year, and that's optimistic.

 

[cozmium]

As far as saving power goes, fans are meaningless. Even huge airflow 120mm ball bearing fans which are generally not even for computer use only use around 3 watts at maximum speed. You could fill the biggest case with them and unless you're near your psu limits it just isn't going to matter.

PWM fans are primarily about reducing noise. I use them on the radiator for my watercooler because it means I can just use something like speedfan to control the speed straight off the motherboard. Without PWM fans you would need a fan controller if you wanted to slow them down.

 

[Someone Somewhere]

It's usually 0.5A@12V, so six watts. Still ridiculously small.

Slowing fans is, as above, all about noise.

 

[dish_moose]

^ +1 - if you are worried about power look at your other components - they use way more power.
-Bruce

 

[DragonChase]

As far as the power issue goes, a PWM and non-PWM fan on full will use about the same amount of power (assuming same fan size, type etc.), but a PWM fan on midway will use less than a non-PWM fan.

Resistoring a fan down will save some power, and some will be converted into heat in the resistors. Still a net saving, but less so.

The other option is to run the fans at 7/5V, which avoids the whole mess.

The amount of energy saved is ridiculously small though. At most a dollar a year, and that's optimistic.

Thats pretty much why i based my post on ''mining currency's" because indeed...you earn nothing by this, except lower noise and in case of mining it can rack up wattage quickly.

 

[ballzley]

@ DragonChase
Thanks, interesting bit about controlling different groups ("loops") of fans through a fan controller.

@Someone Somewhere
Thanks, you answered my questions and implied concerns.

@cozmium
Thank you, interesting info about the PWM - and I thought their strong point was power saving I have a noise/white noise/internal fan device in the same room that I have on all the time for the purpose of having a background noise, so I don't think any of these fans will be a problem then. My stock fans on load sound like a hairdryer on lowest setting, and I'm frankly okay with that.

@dish_moose
Thanks for confirming!

I appreciate your quick and direct answers. The way I see the fans in the case: PWM (pressurized for radiator) fans for radiator in push/pull and for exhaust, and non-PWMs via a fan controller for intakes. Please let me know if I could be doing something better than this set-up. It will be my very first build. I will go ahead and order a few GT AP-45s

Thanks