Fans must be manually spun to start

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  1. Posts : 11,203
    Windows / Linux : Arch Linux
       #11

    Hi folks

    this to me seems an obvious case of insufficient power to start the 3 up concurrently. DC motors (and that's what fans run on) use a load of extra power to start them - once started power requirements reduce drastically.

    For example a typical car starter motor will almost short the battery out to get enough current to start but once the engine is running there's usually zero current drain from the battery.

    Believe me if the fans were defective they wouldn't work at all -- so after cleaning etc the next stage is to check the computer power supply -- you've either overclocked something to bonkers power consumption rates, added a whole slew of new devices for example a new graphics GPU which consumes a load of power or the power supply itself is faulty.

    Check the Wattage of the PSU -- if running at near maximum then any extra load will cause a voltage dip and this could be enough to prevent fans from starting at power on. IMO -if you've connected the fans properly and they are decently clean -- no loads of dust etc on the bearings then it's IMO a PSU problem --these are cheap and easily enough to change.

    With anything electrical never get stuff that's running "flat out" -- it's much better for example to have a 200 Watt PSU running say at 130 Watts than a 140 Watt psu running at 135 Watts.

    The voltage supply from the mains can also play a part -- normally this should be guaranteed by the power company to be within 5% but who knows -- the USA for a major 1st world country has a rather bonkers system of power -- 110 V which means you need an awful lot of thick copper wire to get decent power (remember Ohms Law -- Power in Watts = Voltage X current in amperes -- so if the voltage is lower then the current has to be higher and that means thicker wire to carry it and more heat losses in the grid !!!) and at 60 Hz the inductance losses are much higher than the 220 V 50 HZ systems used in most of Europe and elsewhere.

    (just try going into a store selling kitchen appliances in the USA and ask for an "Electric Kettle" -- the staff will look at you as if you have come from another planet -- to boil water as per Europe you'd need approx 30 Amp fuse - that would be arm thickness !!!!and wire so the kettle would almost be impossible to carry --- totally mind boggoling !!!!!

    Now I can understand the Real reason for "The Boston Tea party" -- it was impossible ever to get a decent hot cup of tea !!!! so hence Starbucks was borne with all that hideous frothy white milk substitute stuff.

    Cheers
    jimbo
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  2. Posts : 455
    Microsoft Windows 10 Professional (x64) Build 19044.1706 (21H2)
    Thread Starter
       #12

    Hi jimbo and everyone,

    jimbo45 said:
    Check the Wattage of the PSU -- if running at near maximum then any extra load will cause a voltage dip and this could be enough to prevent fans from starting at power on. IMO -if you've connected the fans properly and they are decently clean -- no loads of dust etc on the bearings then it's IMO a PSU problem --these are cheap and easily enough to change.
    I was remiss in not mentioning in the original post that all the fans act a little differently. The one with the black fan that's mounted on the power cord side of the unit starts and runs normally. The other two white fans are mounted on the top of the unit. One of these two white fans is more "stubborn" that the other. It takes more coaxing, in the manner of manually spinning the fan, to get it started, after which they run ok until I turn the machine off, or at least I think so because I'm not always checking on them.

    I also notice that the two white fans rotate perceptibly slower than the black one. At least, that's the way it looks to me.

    jimbo45 said:
    Check the Wattage of the PSU -- if running at near maximum then any extra load will cause a voltage dip and this could be enough to prevent fans from starting at power on.
    It's a CORSAIR CX 500. 500 watts.

    I'm not sure what you mean by "running at near maximum". How do I check that? I'm confidant that the voltage supply in my major metropolitan area is not an issue.

    FWIW, this is a Windows 10 desktop. I5 6500 cpu. 16g ram. No battery concerns, so I have the power settings at "High Performance" if that is relevant. Some components have been replaced, but are identical to the originals. I'm not a gamer. Nothing fancy here.

    I don't know exactly when this all started, but as far as I can tell, that "weakest" white fan began acting up first. That was months ago. Then back just before I posted the other day, I discovered both white fans were not running. As I said earlier, when I jiggled the harness and checked the plug connections, which seemed intact. one of the white fans slightly responded, and then eventually began moving, so there's something about the wiring, but could this still more about the PSU? I don't want to be needlessly replacing things.

    This computer is 3 years old, so I don't know why the bios settings would be a factor if they have never been altered, but if it might help, I'll need settings advice

    Here are the images I tires to post earlier. I just noticed that the Fan status on the CHA Fan1 is "N/A". I think all the fans were running at the time. I will recheck

    Note: The CPU fan 1 setting is actually "Standard" (which I guess is a factor regarding the current discussion, but I wanted to mention it). I was fiddling around with the setting when I was in the bios, but discarded the change when exiting.

    Attachment 249628Attachment 249629Attachment 249630Attachment 249631Attachment 249632Attachment 249633
    thanks
      My Computer


  3. Posts : 4,457
    Win 11 Pro 22000.708
       #13

    jimbo45 said:
    Hi folks

    (snip)

    this to me seems an obvious case of insufficient power to start the 3 up concurrently. DC motors (and that's what fans run on) use a load of extra power to start them - once started power requirements reduce drastically.

    (snip)
    jimbo
    Quite an essay.

    I suppose that the PSU could be loaded so heavily that case fans wouldn't get enough volts to operate, but that's very unlikely. Case fans only consume a few Watts at most. For quiet ones, it's more like 1W.

    The fans I have used are of the brushless type, which means there is a fair amount of electronics in them. They aren't just simple DC motors with large start-up currents.

    Wandering off in the same direction as most of the essay:

    Inductive losses at 60Hz? Does the phrase "power factor correction" suggest anything? Reactance is relevant, but it leads to zero power loss, unlike resistance.

    Ideally, we'd all be running DC. No AC power radiating uselessly into space. The technology to change voltage is presumably more developed that it was 100 years ago, so the inability to use simple transformers may not matter so much now.

    I wondered about your "electric kettle" remark. Here's one: https://www.amazon.co.uk/Russell-Hob...gateway&sr=8-3 (I suppose that it's debatable whether the UK is part of Europe.) Astonishingly, it's spec'd at 3kW! All that for 1.7L of water. 3kW would be enough to heat 1.7L of water from 20 C to 100 C in a little over 3 minutes. Europeans must be less patient than Americans.

    Actually, 220V is common in the US, but only for major appliances like stoves and washing machines.
      My Computers


  4. Posts : 11,203
    Windows / Linux : Arch Linux
       #14

    Hi there
    It's not the fans themselves but all the other components that load up the PSU -- for example if there are a load of Spinner type HDD's in the system starting those always initially consume a load of power until the disks reach normal operating speed. personally I'd check the fan wiring to ensure all connections are good and tight -- if these things operate after a bit of manual fiddling then in theory the fans should be OK -- check that the blade edges are still away from any place where they could be causing friction--just a tiny bit of friction would be enough to stop these starting automatically and ensure bearings etc are decently clean and lubricated. If these spin decently with no power on -- easy to test --then problem lies elsewhere in your system -- perhaps even in the monitoring software.

    As for kettles - most people in EU / W.Europe etc don't want to wait even 3 mins for water to boil -- 3 KW kettles are pretty much standard -- you don't have to fill them with nearly 2 Litres of water to make 1 or 2 cups of tea etc -- and it's far more environmentally friendly than using a Microwave as they tend to in the USA to boil a mug of water.

    Cheers
    jimbo
      My Computer


  5. Posts : 4,457
    Win 11 Pro 22000.708
       #15

    jimbo45 said:
    (snip)

    As for kettles - most people in EU / W.Europe etc don't want to wait even 3 mins for water to boil -- 3 KW kettles are pretty much standard -- you don't have to fill them with nearly 2 Litres of water to make 1 or 2 cups of tea etc -- and it's far more environmentally friendly than using a Microwave as they tend to in the USA to boil a mug of water.

    Cheers
    jimbo
    The OP posted that the PSU is a 500W Corsair. Haven't done the arithmetic to see whether it would be overloaded,, but I'd guess not.

    On other matters: while not protected by a US Constitutional Amendment, they'll pry my microwave oven from my cold, dead fingers.

    I don't know what the wall plug efficiency of most microwave ovens is. They offer the advantage of only heating the amount of water that you need (by definition), which partially offsets the efficiency of a direct electric heater. My alternative is my stove, which is propane. That replaces the fear of electrocution with that of explosions.
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  6. Posts : 455
    Microsoft Windows 10 Professional (x64) Build 19044.1706 (21H2)
    Thread Starter
       #16

    What would be an acceptable rpm for those slow white fans I mentioned?
      My Computer


  7. Posts : 8,686
    Mac OS Catalina
       #17

    I still cannot believe this discussion is going on. case fans - Newegg.com Does not matter the RPM, what matters is how much air can be pushed by them to help with airflow through the case and across components.
      My Computer


  8. Posts : 4,457
    Win 11 Pro 22000.708
       #18

    kitpzyxmsir said:
    What would be an acceptable rpm for those slow white fans I mentioned?
    Something greater than zero.

    More seriously, I doubt that anyone can give you such numbers.

    Run the fans at low speed to keep the noise down. If things heat up too much, run them faster.
      My Computers


  9. Posts : 1,494
    Win10 Pro
       #19

    jimbo45 said:
    For example a typical car starter motor will almost short the battery out to get enough current to start but once the engine is running there's usually zero current drain from the battery.
    Hi jimbo45, I believe that is because after the engine starts the alternator supplies the necessary current to keep the engine and accessories running and to also to recharge the battery.
      My Computers


  10. Posts : 19,238
    W11+W11 Developer Insider + Linux
       #20

    All electric motors and indeed all electro-magnets draw several times more power when started up than after magnetic field is saturated. Now, those fans have very small motors so it doesn't impact on circuits around them but you can sometimes see that effect when a refrigerator starts up, lights on same circuit dim or blink for a second.
      My Computers


 

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