Seems to have sold a few sets without any -ve feedback, so maybe just a bad batch - they certainly seem to be spinning off-true so possibly either a defective spindle (alignment), bearing or deformed carcass. Have you tested them when not screwed down to the heatsink?

Probably best to return them as faulty / damaged (doesn't the seller pay return shipping in that case?)

Datasheet: https://filecenter.deltaww.com/Products/Downl … B50x50x10mm.pdf

Yeah I tested them all just by holding them, and the vibration is so bad that it resonated through my hand, through my elbow and made my desk hum. In the first video you can really see how it wobbles at the start. Strangely, if I press the fan down hard against my desk while it's running, there is no humming at all... But I can clearly tell that the rotating part is still vibrating (especially if I gently touch the back of the fan with a finger). This tells me it's entirely in that part (which is floating and visibly wobbles), and probably not the bearings.

All 20 of them did it, with no noticeable variation in intensity. I can also see the unevenness when I turn them by hand if I look flat across the blades.

Problem is, every single one of my fans has the same white number as the one in his picture, so if that's a batch number, that may be why he has them and why they're so cheap. As for negative feedback, I'm hoping you're right and that this is isolated... I can't imagine being able to ignore this vibration when buying new fans, unless you just needed four cheap fans that weren't going to be used anywhere noise sensitive.

So far I haven't gotten a reply from him. I'll keep trying. I would prefer to just have them replaced, but these are nearly worthless to me. I have a few dozen boards I need to outfit and many will eventually be resold. I certainly can't stand the sound, and I can't sell a board with a fan that gives a PC that nice "year 2000 high speed CD-ROM idling" buzz the entire time it is running. 🤣

Thanks for your help. Any other feedback about the dynamics of what could be happening inside the fan would be appreciated. I'm not very well educated on the inner workings of fans, aside from pulling out a plug and oiling them (which you can't do with these, even if that were the problem).

The seller didn't give much of a reply when I mentioned this to him. He said he hadn't gotten any complaints about the others that he has sold, and when I sent him the videos of the fans wobbling he just said "please return".

So, I'm going to send them back. I asked him if he could test any others to see if they have problems, but this transaction has left a bad taste in my mouth with these, so I don't think I could get myself to order more unless someone else got ones that worked properly. I almost wonder if they were damaged in shipping? All 20 were crammed into a stiff plastic zipper bag and were sort of at an angle. Maybe they got messed up from that.

I won't give bad feedback, since he's letting me return them and doesn't seem to speak a lot of English, but I personally would recommend staying away from these. Even if they do work and you are putting them somewhere that all the noise won't that big of a problem, I doubt they'll last as long as they should.

Wobble is sign of rejects, storage or shipping damage. Try to obtain other brand like Nidec or San Ace/Sanyo, NMB/NMB-NAT, YS Tech. They were better quality. The Delta fans are not innovative even their newest one were poorly done and lot of mold flash, sloppy. And performed poorly.

I had seen this with few fans I got from chinese, rarely was fake or very low quality reproduction, particularly Delta.

Cheers,

Thank you! I really appreciate the input. I had my suspicions that these weren't fakes and were just really bad quality from a well known brand. I was looking at Nidec or San Ace next because I have a lot of those that still work fine after many years.

I also have ARX and AVC fans that run perfectly.

I have a couple of original boxed AAVID fan+heatsink combos but they don't seem to have aged as well, despite being unused.

Since you're here, do you have any recommended 50mm fan models, or any places you buy them from? In particular, I'd like ones with either a 3pin header that fits a standard PC fan connector, or a 4 pin molex. Lower RPM fans would probably be best, since these socket 7\370 chips don't need crazy cooling to run at stock speeds.

Trick is try them on 5V, these 2 and 3 wire fans responds well and quieter. YS Tech also have 24v in 50mm size but will run on 12V and much quieter too. NMB, Nidec and YS Tech, Sanyo/San Ace available in 50mm. Some are 24V can be run on 12V too like I said for reduction in voltage means quieter and last longer.

Anything of these brands we liked, doesn't matter. 50mm is kind of oddball. YS Tech usually do and is easier to find and was a frequently used on early coolermaster heatsinks back in the day. AVC is kind of good but noisy on 12V.

YS Tech plenty of choices for 50mm size on ebay and not too expensive.

Cheers,

pentiumspeed wrote on 2021-02-20, 22:43:

Trick is try them on 5V, these 2 and 3 wire fans responds well and quieter. YS Tech also have 24v in 50mm size but will run on […]
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Trick is try them on 5V, these 2 and 3 wire fans responds well and quieter. YS Tech also have 24v in 50mm size but will run on 12V and much quieter too. NMB, Nidec and YS Tech, Sanyo/San Ace available in 50mm. Some are 24V can be run on 12V too like I said for reduction in voltage means quieter and last longer.

Anything of these brands we liked, doesn't matter. 50mm is kind of oddball. YS Tech usually do and is easier to find and was a frequently used on early coolermaster heatsinks back in the day. AVC is kind of good but noisy on 12V.

YS Tech plenty of choices for 50mm size on ebay and not too expensive.

Cheers,

Thanks for the tip. I have run 12v fans on 5v with an adapter, but never thought about getting 24v fans. That's much simpler than having to mess with adapters.

Sadly, I think finding a good cheap supply of 50x10mm 24v fans is going to be a stretch. I'm not seeing any that also have 3pin motherboard-style connectors. I'll definitely keep looking though.

How do you feel about Sunon? I have some Sunon fans that were purchased in the mid 90s that still work, and I see them pop up from time to time.

I have read about a lot of people wiring fans for 7v from a power supply by just getting a basic 4 pin molex to 3pin fan adapter and switching the pins to 5v and 12v. Has anyone ever run into issues with this? I would never do this with a splitter that could be used on another device accidentally (shorting 5v to ground is probably bad) but with a straight through adapter, it seems fairly safe. Still, I have read that some people were concerned about making a power supply do this, as it was never intended to be run this way.

Alternatively, have you guys had success running a simple resistor inline with a fan connected to a motherboard header? Does the tachometer in the fan still work properly for 3pin fans or will it be inaccurate or non functional? I ask because it is much simpler to do the 7v molex thing than to add resistors to fan extensions, so if there is no down side to that and neither will allow for fan speed monitoring, then I would opt for the molex-rewire method.

If there are any other methods that are really cheap, but above all reliable and safe, let me know.

I have seen sellers on amazon and ebay selling large piles of fan speed reducers (3 pin male to female with a resistor inline with the 12v wire), but I don't know if I trust the build quality of them and I have no idea what value or wattage rating the resistors are that they're using. One bad solder job or one undersized resistor could make for a very bad day. If you guys have used them though, let me know. I might consider it if they're seen as reliable overall. I'd be using them on small 50mm fans rated for 2.04 watts (0.17 amps).

Yeah, I've done the 5v / 12v pin swap in the past, and used it on a number of PSUs without (apparent) issue tho I did so having read the same type of warnings you refer to. I'd also say that I found results varied with the fan model - some seem to benefit whilst others seemed no different when run at 7V or on a proper 5v adapter.

PC Hoarder Patrol wrote on 2021-03-04, 05:49:

Yeah, I've done the 5v / 12v pin swap in the past, and used it on a number of PSUs without (apparent) issue tho I did so having read the same type of warnings you refer to. I'd also say that I found results varied with the fan model - some seem to benefit whilst others seemed no different when run at 7V or on a proper 5v adapter.

Thanks for the tips!

I will say, I was just playing with a system using a molex adapter modded to 7v and it seemed to be working great (speed was between 5v and 12v, as expected) but I was doing some very minor tasks and I noticed the fan speed fluctuating? That was a bit concerning. The power supply is certainly capable of handling the load (Seasonic 350ET, with 20A on the 5v rail, running a 440BX board with a Socket 370 Celeron 900Mhz and an S3 Trio64), so I'm not sure what was causing the fluctuation. Running at 5v it still seems to be cooling it sufficiently with no fluctuation... and boy is it quiet.

I found a nice page with max temperatures listed for various CPUs. On an open bench with no other cooling my Celeron 900 is only hitting 38C after running some tests for half an hour, with the CPU fan at 5v, so I think this is plenty for this setup.
http://www.heatsink-guide.com/maxtemp.htm

I may opt for just getting a pile of molex to 3pin adapters and modding them to 5v since it takes all of 5 seconds with a pin removal tool. At some point I'll try my hand at making some 3pin adapters for the convenience of using them with motherboard headers.

I found a very nice and simple 17-year-old guide for calculating resistor values here:
https://www.overclockers.com/forums/showthrea … ple-Electronics

I'll copy and paste them here in case that page is ever gone.

1 11-26-04, 02:26 PM #1
2TheWesson
3TheWesson is offline
4Member
5TheWesson's Avatar
6
7Join Date
8    Dec 2003
9Location
10    Portland, OR usa
11
12DIY Fan Slowing with Simple Electronics
13
14    Here's a very nice link with a lot of information about fans & how to add very simple electrical components to slow them down.
15
16    (My apologies if it's been posted a zillion times.)
17
18    http://www.cpemma.co.uk/index.html
19
20    That's the link that finally explained to me exactly how a resistor drops voltage.
21
22    Simple how-to for slowing fans by 1/2 (12v to 6v) with a single resistor:
23
24    Summary: To drop fan voltage by 1/2 put in a resistor equal to the fan's resistance.
25
26    1) Calculate resistance of fan with simple formula. R = Volts/Amps. Volts and Amps are usually right on the fan's label on the hub. Volts for PC's is always 12v for fans.
27    2) Buy a resistor equal to 'R' ohms, above, of sufficient wattage. Needed wattage of the resistor is V * V / R, where V is the amount of volts being dropped (in this case 6, when working with 12 volts.) Buy a resistor with 2x the Watt rating it technically needs, so it doesn't get hot.
28    3) Put it inline with the fans power (black or red wire). Direction doesn't matter. Your fan will go from 12v to 6v, turn at half speed, move half the air, and sound half as loud or less.
29
30    Example:
31    I have a 0.25 amp Panaflo 120mm L1A. Resistance = 12/0.25 = 48 ohms. So I am looking for a resistor (approximately) 48 ohms. Watts for the resistor is 6v * 6v / 48ohms = 0.75 Watts. To be safe, I'll get a 2 Watt resistor, at about 50 ohms.
32
33    the problem with the resistor method is that it will drop *less* on a less powerful fan, and more on a more powerful fan. But it will still be approximately what you want, over a range of fans of different amps.
34
35    40 ohm resistor on 0.1A fan: down to 9v
36    40 ohm resistor on 0.2A fan: down to 7v
37    40 ohm resistor on 0.3A fan: down to 6v
38
39    You could also use the "7 volt mod" (described on that link as well.) However, putting in a resistor will be usable with mobo fan headers. I plan to get some fan cord extensions, and will make them into "volt dropping" extensions. Less wire clutter than the "7v mod" feeding fans off the PS.
40
41    There are also better ways to drop volts which are still fairly easy, described on that site, maybe I'll try some of them. Resistors are extremely cheap, though, compared to fan controllers. And small and unobtrusive
42
43    the wesson 
44
45Reply With Quote Reply With Quote
4611-26-04, 02:41 PM #2
47TheWesson
48TheWesson is offline
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52Join Date
53    Dec 2003
54Location
55    Portland, OR usa
56
57And ... how does a resistor drop voltage?
58
59    The formula for a resistor dropping voltage is also explained in the "Choosing a Rheostat" stickey. But here goes my own version.
60

61    You have 12 Volts. You want V volts. How much resistance do you need?
62
63    Fan resistance R1 = 12/Amps. (Amps is amps of fan, from label.)
64
65    R2 is the ohms of the resistor we will buy.
66
67    R2 = R1 * (12-V) / V
68
69    How many watts on the resistor?
70
71    Watts = (12-V) * (12-V) / R1
72
73    Multiply that by 2 for the resistor you will buy, just to be safe.
74
75    anyhow I think I have this right, but plz correct me if you see mistakes.
76
77    Example: I have a 0.3 Amp fan I want to drop to 5v.
78    R1 (fan resistance) is 12/0.3 = 40 ohms
79    R2 = 40 * 7 / 5 = 56 ohms
80    Watts needed = 7 * 7 / 56 = 0.875
81    So a 2W, 56 ohm resistor is what I'm looking for.
82
83    This checks out because a Zalman adapter for dropping one of their fans to approximately 1/2 speed happens to include a 56 ohm resistor ...
84
85    the wesson 
86

5v to 12v shouldn't do any harm I guess. I use that trick a lot and haven't had a single issue with that.

The ground wire is basically a 0v line, and all that matters is the voltage difference.

Technically you could even connect+12v and -12v to get a 24v fan run at maximum speed
Or+5v and-5v for a 10v experience.
Or +12 and -5 for 17v
Or +5 and -12 also for 17v
And so on.
(if there lines can deliver enough juice ofc)

The only catch that could occur, is when some weird PSU requires that all lines are connected to a + or - source and to gnd specifically. I haven't seen it.

FYI Fractal design has 50mm 12v fans
https://www.fractal-design.com/products/fans/ … -r3-50mm/black/
Not Noctua quality thats for sure.
But certainly better then average.