NeverBackDown
AMD Enthusiast
I want to know how to find out fan speeds at a certain volts. So i can find out roughly the static pressure of those rpms and therefore use them in a watercooling setup i plan on doing.
Calcuationg Fan Speeds
- Thread starter NeverBackDown
- Start date
I want to know how to find out fan speeds at a certain volts. So i can find out roughly the static pressure of those rpms and therefore use them in a watercooling setup i plan on doing.
jamesriley94
New member
You really don't need to go into that much detail tbh.
Massively overthinking things to say the least...
When you run fans at low speeds - let's say 5v. There will be such little difference between performance of each it really wouldn't matter. I mean, even if at 5v one fan had a static pressure of 1, whilst the other was at 0.5, that will only equate to 1 or 2 degrees increase in temps - if that. If you have enough rads, the rads don't even get hot as the heat dissipates well before they have a chance to.
Take mine for example -
When I had my 3770k and 670 both on the 360 rad, when both were being stressed on Heaven or something, that's when the rad got warm, and so fan speed may matter a little more - by which I mean, the difference between 5v and 7v equated to about 5-10 degrees difference.
However, after adding a second 240mm rad, even under load, the heat is dissipated so quickly that the rads never get hot, and so even under load, the difference between 5v and even 12v is only a couple of degrees.
If you have enough rads, you can get away with running near enough any fan you want, on as low a speed as you want.
If you were running a CPU only on a single slim 240mm rad - like the H100 for example, then the fan choice will make much more of a difference. But in custom loops, if you do it properly and add a decent amount of rad space, then you shouldn't have any problems at all.
For reference, my CPU is at 4.6ghz (1.3v ish), and my 670 is at 1200mhz - and with every fan in my case at 5v, and the pump at the lowest speed setting, temps don't really go above 65 degrees C. Any higher overclocks, and temperatures increase because the waterblocks are unable to absorb the heat quick enough for the coolant to take away the heat. Even at these values, changing my fan speed from 5v to 7v or 12v makes only a few degrees difference to core temps, as the rad space is easily enough anyway.
NeverBackDown
AMD Enthusiast
So what fans to get are the question now? If all fans at around 7volts don't make much of a difference then why bother getting high end fans?
jamesriley94
New member
No no - I've probably not been clear enough...
In most cases, such as on AIO loops like the H100, or heatsinks like the D14, or very small custom loops, the fans do make quite a big difference. But, this is because the heatsinks or radiators themselves get hot as they absorb heat, and so need high pressure fans to push out that heat as fast as possible.
But, if you do a custom loop properly, with a lot of rad space, then the radiators themselves never actually get that hot and so massively powerful fans aren't needed to exhaust the heat.
As long as you have enough rads, the fans don't make such a big difference.
What hardware exactly are you wanting to cool, and in what case?
NeverBackDown
AMD Enthusiast
This loop will most likely be after Christmas as I might be changing hardware around then when the new 8xxx cards come out if they are comparable to the 7xx cards.
Other than that in a R4 i plan on getting a RX240 D5 kit for the front and a ST30 240 rad in the roof with a CPU and maybe a gpu depending on blocks. I know fans won't matter for this loop but I really just wanted to figure out the speeds and such.
Other than that in a R4 i plan on getting a RX240 D5 kit for the front and a ST30 240 rad in the roof with a CPU and maybe a gpu depending on blocks. I know fans won't matter for this loop but I really just wanted to figure out the speeds and such.
jamesriley94
New member
If you run fans at 7v there, you shouldn't really have any problems no matter which you choose (assuming the process of hardware getting more energy efficient remains the same).
NeverBackDown
AMD Enthusiast
True but then again IF i get the RX240 D5 kit now for a cpu only loop(would be temporary) then you think 7v with an OC around 4-4.2( don't know volts yet but my cpu seems slightly better than others) i could get away with it?
jamesriley94
New member
Easily yes.
What CPU do you have? If Ivy or Sandybridge - you should easily be able to manage more than that.
What CPU do you have? If Ivy or Sandybridge - you should easily be able to manage more than that.
NeverBackDown
AMD Enthusiast
3570k at 3.6ghz with 1v(vdroop goes from .972-.992) with a stock heatsink. It's much quieter than one might think. Surprisingly
jamesriley94
New member
Most Ivybridge chips can get up to 4.5/4.6ghz before temps become unabsorbable by blocks and coolers and so temperatures rocket up then.
You should be able to get to aht mark easily enough
You should be able to get to aht mark easily enough
NeverBackDown
AMD Enthusiast
I just don't want to push the OC too far as I'd like to keep the rig as long as possible. Thanks for the help!
So in other words just forget about calculating fan speeds, volts, etc. and just grab some decent fans on 7v? If so then what fans? I had another thread asking this question but it died pretty quickly... lol
So in other words just forget about calculating fan speeds, volts, etc. and just grab some decent fans on 7v? If so then what fans? I had another thread asking this question but it died pretty quickly... lol
jamesriley94
New member
4.5ghz should be fine tbh - assuming you can get that under about 1.25v (which most Ivybridge chips can for 4.5ghz)
Fan choices:
Bitfenix Spectre/Spectre Pros, Scythe GTs, Noctua NF-F12s, Noctua NF-P12, Silverstone AP121/AP123, most Enermax fans, Akasa Apaches, Noiseblockers, Phobyas....
I'm sure many others will add to this list.
Fan choices:
Bitfenix Spectre/Spectre Pros, Scythe GTs, Noctua NF-F12s, Noctua NF-P12, Silverstone AP121/AP123, most Enermax fans, Akasa Apaches, Noiseblockers, Phobyas....
I'm sure many others will add to this list.
NeverBackDown
AMD Enthusiast
I have been debating for the past few days on the Cougar Vortex 1200rpm model or the AP123s and lastly the Sp120 QE.. Not sure which
jamesriley94
New member
I have been debating for the past few days on the Cougar Vortex 1200rpm model or the AP123s and lastly the Sp120 QE.. Not sure which
Yeah, Cougar and Corsair (always forget Corsair) are meant to be good too.
Whichever is cheapest / you like the look of.
You can't really go wrong with any of the ones mentioned above.
NeverBackDown
AMD Enthusiast
They are all around the same price so that's my issue lol. Though i will also need to buy a molex to 3x 3pin 7v cable from bitfenix as my built in fan controller can only 3 fans at once.
Edit: Are Bitfenix Spectre Pros quiet at 12v? Was just curious as I am now looking at the AP123 and BF PRO, and lastly the CougarVortex fans. all 120mm btw.
Edit: Are Bitfenix Spectre Pros quiet at 12v? Was just curious as I am now looking at the AP123 and BF PRO, and lastly the CougarVortex fans. all 120mm btw.
Last edited:
easier to multi .41666 to your rpm for 5v and
easier to multi .58333 to your rpm for 7v for a linear projection.
NeverBackDown
AMD Enthusiast
NeverBackDown
AMD Enthusiast
Oh i see.. I wouldn't say my way was "long" because you then have to take my calculations and then use what you got to multiply the rpms... SO really the same.
But what's your take on the fans i perviously listed in post 35?
But what's your take on the fans i perviously listed in post 35?
no BFS pros are not silent at 12v (1.5m still audible)
AP123 are quieter than BFS pros, but neither move air like the cougars. with
that said, the cougars are choppy loud at 12v. under-volted 7v they are so-so
performers and still a lil windy in noise.
what are the conditions these are to be used as? case fans or rad/HSF fans?
