Question Which motors are best for case fans: advanced hydraulic bearings, brushless, maglev, or other?

[Coyle]

Which last the longest, quietest, most cfm/wattage, etc?

 

[Paperdoc]

I can't tell you which bearing system is best. But you will find that all computer case fans and CPU cooler systems now use the brushless design, which has nothing to do with bearing lifetime. However, sucvh units cannot have brushes wearing out, althouhg they do have new electronic components that might fail in time. However, those items normally last MUCH longer that mechanical components, so they rarely are a cause of failure.

 

[Coyle]

Yes, I understand brushless motors a bit more as I have an electric bike and still have the original brushed hub, but the brushless don't have brushes but as you mentioned do have other electronic components, in e-bike case controller is more expensive. Hmm, I might have just realized what I was wanting to know, which is I saw higher wattage on the hydraulic bearing fans than the brushless but brushless use less power than mechanical, so I am thinking I can get the same cfm from the lower wattage brushless fans, does that seem correct? Replacing an Dell oem case fan, mine isn't very powerful and had a psu failure recently, has been running 8 years 24/7 so could be unrelated but can't hurt to replace the fan with new, are inexpensive new pulls off eBay and those were the 3 choices. Guess not even get into what Maglev is.

 

[thesmokingman]

The NIDEC SERVO motors they use in the GT fans.

 

[mindless1]

TLDR; Get 25mm thick NMB Dual Ball Bearing Fans having the RPM that matches the application. There are other decent major brands but I have had very good results with them. They run practically forever.

You are just using marketing terms for sleeve bushings. Some are better, patented by major manufacturers and include an oil reservoir at the end which greatly increases their lifespan, but ultimately the only reason to choose a sleeve bushing fan is because you have one of two situations:

1) High impact environment, high enough that it doesn't really apply to personal computers at all, would potentially deform ball bearings.

2) Want to sacrifice lifespan for lower noise in the higher frequency spectrum. They'll both have nearly identical noise in the mid to lower spectrum, depending on the other design parameters such as RPM and blade shape as well as nearby obstructions causing turbulence.

Besides these two, dual ball bearing fans are superior (given similar quality) for lifespan and heat tolerance, and resisting dust contamination.

Wattage rating is not very related to any of this, you just happened to see too small a sample of fans to realize it. Brushless do tend to use a little less power at the expense of needing a controller, but it is irrelevant for this discussion because any fan meant for a PC is brushless.

Wattage doesn't really matter for another reason, that the power difference is trivial on a system consuming at least dozens of watts and that difference usually being less than a quarter watt. Realize that the wattage on a fan label is significantly higher than its normal free air current would cause, more like a maximum stall/spin-up current so at most you could only generalize that with the same fan design and size, a higher wattage means it spins at higher RPM.

Focus on these three areas:

Amount of airflow needed vs noise. Any decent quality fan should provide specs for these, if not at the seller listing then at the manufacturer's website. Most of the noise comes from turbulence not the bearing, so determine what the maximum airflow you're doing to need is, and whether you have a suitably matched fan controller to throttle the RPM down when less airflow is needed.

Size. Obviously. This includes thickness, with 25mm typically being the best match for a typical PC because thinner produce more bearing wear and need significantly higher RPM, while thicker than 25mm (except in very large fans) tend to be more powerful than needed and can't even be spun at very low RPM without producing a ticking noise. There are exceptions, but those tend to be with a controller matched carefully to the fan.

Noise vs lifespan. Dual ball bearings will last longer, sometimes MUCH longer, but make a high pitched bearing whine. Sleeve (bushing aka) bearing fans should not be mounted in horizontal orientation if you want decent lifespan from them. An excessively worn sleeve bearing fan can be louder than a ball bearing fan, and once the bearing starts to wear, you'll need to relubricate it every so often.

The other components in a brushless PC fan practically never fail unless you have a mains AC power surge or pretty severe PSU failure. Otherwise (unless you get them wet somehow), it's practically always the bearing that fails long before the control circuit, unless it's some horrible quality generic junk fan and it was a quality control rather than a wear problem.

 

[Coyle]

The fan size is 80x80x20, 4 wire 5 pin; proprietary to Dell, I found 3 manufacturers: AVC who use they list a Advanced Hydraulic Bearing, Sunon--Maglev, and Foxconn Brushless. All are around 4 watts; the front case fan in it now is so weak, maybe supposed to be but like if I put a tissue up to the case grid it doesn't even hold it there. Do you think one of these fans are any better than the others?

 

[john3850]

Over the years the cases that took the 80mm fans were recut to accept a 120mm.When buying fans I worry only about the cfm they can move and try to get fans between 80 to 110 cfm.Your fan speed can always be lowered but not increased.Music and headphones tend to reduce the fan noise

 

[Coyle]

Over the years the cases that took the 80mm fans were recut to accept a 120mm.When buying fans I worry only about the cfm they can move and try to get fans between 80 to 110 cfm.Your fan speed can always be lowered but not increased.Music and headphones tend to reduce the fan noise

I ended up getting a much higher powered fan than I meant to; the one in my case was only 1.5w, while the one I purchased (4 wire 5 pin instead of 3 wire...) like in the pic is 4w. It doesn't work with my motherboard controls; installed speedfan and got it to work at a min' of 67% which is 3000rpms, don't know how that converts into cfm but it does move a lot more air than the old one--it's a bit louder too. I just found out that the case fan is temp' controlled so the old one would've run faster if it had needed to. There are sellers on eBay have all the specs for my case fan except they are 4 wire instead of 3, still a 5 pin, so now that I have the original out of the case I found an exact replacement for it, figure for $5 I might as well get it now while it's fresh in my mind for if I need it later on.

 

[HerrKaLeu]

this PSU 101 has a great section on fans as well. note some bearing types don't like horizontal installation, which may be a limit.