Nexus 120mm - How slow?

Chris.Day · Post by **Chris.Day** » Wed Jun 01, 2005 10:10 pm

How slow can most people get the Nexus 120mm running? I have to have mine at 780RPM to have it reliably start up (and it's too loud at this speed). I have previously set it at around 670RPM and it would start most of the time, but occasionally wouldn't start, or it would just stop (and when it did it would cause my DTT card to break up from interference).

At 780RPM, it's bearable, and it's not an unpleasant sound, but it's a little louder than I hoped for (too much whooshing). The Nexus NX-4090 has a similar sound at it's quietest speed.

Thanks

teejay · Post by **teejay** » Thu Jun 02, 2005 2:00 am

I'm not sure if my situation is of much use to you since I do not use straight voltage mods to slow down my fans, but here goes. On my main rig with a T-Balancer the fans run fine at 30%. The T-Balancer software reports this as 350rpm, but that simply calculates the percentage of the perceived maximum speed... I'm not very sure thats accurate though. On my other machine, they run at ~500rpm, which is the lowest I can get out of a Coolermaster Aerogate II with a Zalman fanmate in-line at the lowest setting.

Since both controllers spin the fans at full speed directly after startup and use PWM to control the fan speed afterwards, this might not be of much use to you. I do agree that ~650rpm is the maximum speed at which I want to have these babies spinning... above that I start to notice air noise. How do you regulate your fans currently? What speeds can you achieve after they've started without stalling?

I have seen some relatively simple DIY electronic circuit schematics around the forums to create that speed burst directly after start-up, maybe that's an option for you?

Post by **Ralf Hutter** » Thu Jun 02, 2005 10:03 am

All of mine will start up 100% reliably at around 710-720rpm.

nici · Post by **nici** » Thu Jun 02, 2005 10:21 am

Well the DFI mobo starts it up at 100% so unless something is blocking it for some reason it will spin up, after that i can lower it to about 430rpm or so and be shure its spinning. 30% speed is 280rpm and it does spin reliably, but it hardly moves any air and you cant hear it under 650rpm anyway when its in the case.. The mobo lets you adjust the speed form 0-127%, 127% results in 1120rpm. 100% is 950rpm. and it doesnt "calculate" the percentage of perceived speed, maybe the T-Balancer does, but as the rpm reading gets lower if i slow the fan with my finger, and takes a while to raise/slow down when adjusting it should be checking the rpm pulses and calculating it from there.. I would think its strange if the balancer would do it differently.

Anyway, to always get the fan to start reliably and still have it xpinning slow, your easiest option is PWM. Mobo connecors can ofter be contolled this way, if not then your best bet would be to buybuild a PWM controller. This way you can have your fans start at 100% and then slow down to whatever you want.

You could also do this without PWM, with a time-delay. I dont feel not-tired(whats the word?) enough to design one now, but it should be pretty easy to make a circuit wich puts out 12V for lets say 4 seconds after getting fed with voltage, and then switvhing to desired speed and holding that speed until you turn it off and start again.

alleycat · Post by **alleycat** » Thu Jun 02, 2005 10:58 am

I don't know if this helps, but I think many people are using 120mm fans unnecessarily. Because it's the amount of air being moved that's causing the problem, it is probably easier to run an 80mm fan at low speed for reduced airflow, since the motor noise of Nexus fans is negligible at these speeds.

nici · Post by **nici** » Thu Jun 02, 2005 11:29 am

Yeah well, both 120mm Nexus fans i have have next to no motor/bearing noise. Next best in this regard was the Glacialtech SilentBlade, the Papst(some "18dB" model) being the most expensive and having the highest and the most annoying type of motor/bearing noise is definately not my favorite. You might get a good sample, you might get a bad one.. I got a bad one probably.

If no motor or bearing noise is present, a 80mm cant move as much air as a 120mm at the same level of noise. Now i would much rather have the 80mm nexus at say 10V than the 120mm Papst i have at 5V, but i wont change my 120mm nexus for a 80mm one because it simply cant move the same amount of air, and considering neither have noticeable motor or bearing noise its clear wich one is more suitable for case ventilation. Now if you have place for two 80mm fans it might be different, but most cases dont and neither does mine. I have two of both sizes. I think ill have to stop posting for today, my messages seem to go somewhat off-topic and get quite long.. sorry about that.

niels007 · Post by **niels007** » Thu Jun 02, 2005 12:18 pm

It seems that the low speed Yate Loon starts at a lower RPM than the Nexus. In my case the nexus also needs to be set at ~700RPM before it spins up, but the 'Tech Solo' branded Yate Loon starts a lot lower. It has no speed sensing but I'm guessing 500rpm. Its just as good as the nexus, certainly not noisier at the same RPM..

Chris.Day · Post by **Chris.Day** » Thu Jun 02, 2005 12:47 pm

Thanks for all of the replies. I'm using straight Zalman Fanmate 2 on it. I prefer the CPU fan to be controlled automatically by SpeedFan (only the CPU fan header on my board has PWM control) - that's an 80mm Nexus on a Scythe FCS-50.

One thing I have noticed, the RPM of the exhaust rises about 20-30 when I remove the side panel. Is this normal behaviour or is it struggling for air? I'm using an Evercase ECE-4252.

Seal · Post by **Seal** » Fri Jun 10, 2005 2:27 am

hey, dont mean to hijack the post or anything but i kinda need some similar advice too. I just ordered 3 of these fans for my system 1 for exhaust, 1 for psu and 1 for the watercooling radiator. the question i have is what are the rpm values for this fan on 5v and on 7v? i will be hard wiring my fans to the molex connectors so will not be able to see rpm values. also do these fans have 100% reliable startup at 5v?

thanks

brigitte · Post by **brigitte** » Fri Jun 10, 2005 2:36 am

Mine won't start at 5V.

Deathlife · Post by **Deathlife** » Mon Sep 05, 2005 6:30 am

It's the first time I hear about "PWM" What does it stand for?

Do the rheobuses out there have this feature? I mean, start every fan at 100% for a reliable start up and then descend the rpm to the desired settings.

Also, is it definetely Nexus better than Paspt noise-wise? (compared to an emb-Paspt 26dB undervolted ).

Ackelind · Post by **Ackelind** » Mon Sep 05, 2005 6:38 am

How many rpms would you guys guestimate the 120mm nexus does at 5.5V? I have a zalman resistor inline with my fan, but my mainboard seem to report different rpms every time I check.

Shadowknight · Post by **Shadowknight** » Mon Sep 05, 2005 7:11 am

Mine will start reliably at about 650rpm. In my current rig I can't even hear them at 780rpm, so there's no point undervolting them anymore than I currently have.

Ackelind · Post by **Ackelind** » Tue Sep 06, 2005 5:08 am

I find mine quiet at 5.5V, but far from silent. Is it my room that has very low ambient noise, are the nexuses I've bought defective, or is my hearing just extraordinary?

StarfishChris · Post by **StarfishChris** » Tue Sep 06, 2005 7:05 am

Max speed should be 1000rpm. What are you getting at 5.5v? It should be around 500RPM (voltage and rotation speed is fairly linear).

nici · Post by **nici** » Tue Sep 06, 2005 7:51 am

Ackelind--> Is the noise you are hearing a whoosh or clicking/scratching or some kind of other mechanical noise? A nexus at 550rpm is very quiet when it comes to wind noise.. Inaudible in most situations, and i have low ambient noise with the puter right next to me on the desk.

JonV · Post by **JonV** » Tue Sep 06, 2005 8:50 am

StarfishChris wrote:Max speed should be 1000rpm. What are you getting at 5.5v? It should be around 500RPM (voltage and rotation speed is fairly linear).

Were they exactly linear, 5.5V would imply 458rpm. From what I can remember mine runs below 400rpm at 5V.

Ackelind wrote:I find mine quiet at 5.5V, but far from silent. Is it my room that has very low ambient noise, are the nexuses I've bought defective, or is my hearing just extraordinary?

Mine is at the back of the case below a thick desk and is inaudble even at 7V. At 5.5V I would have to put my ear within a foot of it to hear it. But of course, if you have several, say 3 or 4, they're going to make more noise added up.

nici · Post by **nici** » Tue Sep 06, 2005 8:57 am

Listen to music at unhealthy volume and dont worry about da fan noise.

BenW · Post by **BenW** » Tue Sep 06, 2005 11:33 am

I made a little 5V/12V switch by following a guide here on SPCR. Means i can start the fan at 12V and turn it down the 5V easily. Also means i can turn it up to 12V when i start something graphics/cpu intensive

vertigo · Post by **vertigo** » Tue Sep 06, 2005 1:42 pm

Listen to music at unhealthy volume and dont worry about da fan noise.

Blasphemy! Off with his head!

nici · Post by **nici** » Wed Sep 07, 2005 6:58 am

vertigo wrote:
Listen to music at unhealthy volume and dont worry about da fan noise.
Blasphemy! Off with his head!

Hehe

If you havent noticed yet, im more or less obsessed with silent computers but dont want to sacrifice performance, and to add to the challenge i want air-cooled.. Theres several Gallery threads about my nutty projects

I have three 120mm fans in my system currently, i´ve been experimenting with different setups in the P180 and this seems the best so far. Two 500rpm fans sucking air out and one 500rpm fan keeping the Phantom cool.

Ackelind · Post by **Ackelind** » Thu Sep 08, 2005 10:24 am

JonV wrote: Mine is at the back of the case below a thick desk and is inaudble even at 7V. At 5.5V I would have to put my ear within a foot of it to hear it. But of course, if you have several, say 3 or 4, they're going to make more noise added up.

I can clearly hear a difference when turning the knob on my fanmate, I start to hear it clearly at roughly 7-8V. I have two nexuses at the top/back of my P180. The top is constant at 5.5V, the back is fanmated. I can hear som whirring if i have my head right at the fan, but not from a few feet away.

I am beginning to think that the low "woosh" that I hear from my case is actually my two Spinpoints in the lower chamber instead.

Deathlife · Post by **Deathlife** » Thu Sep 08, 2005 10:32 am

Does anyone have Yate Loons? Are they really silent like the Yate Loon "Nexus"?