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PWM vs DC

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This topic contains 24 replies, has 5 voices, and was last updated by keith with the teef 3 weeks ago.

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  • #38257

    keith with the teef
    Participant
    @thinktank

    Pluse wave modulation verse Direct current.

    I was wondering what is your prefered settings when it comes to controling your fans on your PC and why.

    For Me its DC because that pulse thing just seems a little OTT?

     

Viewing 20 replies - 1 through 20 (of 24 total)
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  • #38259

    Dave Rice
    Moderator
    @ricedg
    Forumite Points: 4,183

    I just leave it on the motherboard knows best ๐Ÿ˜€

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    #38262

    Wheels-Of-Fire
    Participant
    @grahamdearsley
    Forumite Points: 4,072

    PWM is how a dimmer switch works and is usually best but it depends what fans and fan headers you have.

    Im with Dave though, unless you have some super duper fans, just leave it alone ๐Ÿ˜

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    #38281

    keith with the teef
    Participant
    @thinktank
    Forumite Points: 2,217

    I actually do have superdooper fans. The funny thing is this. If you configure them to: system, cpu or chipset andย  My fans shift twise as much air as generic at the same speed and yet becase of the configure options that means unless I lock them down they will Go like a dyson hand dryer and for the most part acheive nothing except mabe slow down the GPU fan 2hundred RPM and probabley starve in my case the PSU of grabable air. ๐Ÿ™‚

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    #38285

    Dave Rice
    Moderator
    @ricedg
    Forumite Points: 4,183

    The mega machine bits arrive today and because it’s intended to one day overclock it (no real need to now, part of the future proofing) I’ve ordered two 120mm fans for the front of the Bitfenix Nova case. They’re just BitFenix Spectre PWM jobs as I thought they might as well all match. Unfortunately no window or light show on this one as it’ll be hidden away under a desk.

    The Gigabyte B450 Gaming X has enough headers for one each and I know from their Auros boards that there will be some fancy fan control available. I’ll have a play when stress testing it.

    I did think of a basic AIO water cooler for the R7 2700X but as I think I mentioned elsewhere the bundled Wraith Prism kept an R5 2600 well under control so I’ve left it. I’ll know if that was a good decision by the end of the day ๐Ÿ˜€

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    #38286

    Les.
    Participant
    @oldles
    Forumite Points: 1,087

    In reality, unless you use a battery and resistor, or an old design series or shunt controller, you are getting PWM. If not at the fan, a bit higher up the food chain. PWM is used all over the place, in PCs and almost everywhere else, because it is energy efficient. If you need say a steady 3v DC for the fan speed at a particular moment, then you could have a short pulse of 6v, then an equal length pulse of zero volts, giving the required average on 3v. In extremes cases (unlikely with a little fan), the combination of higher voltage and the very rapid voltage rise can overcome the insulation of the device and it is RIP. (Inverter use for three phase motor control works with a PWM output following the general sine wave shape of the “natural” voltage curve, but of course with higher instantaneous voltage level. Some older three phase motors after many decades of “normal” use were found to fail rapidly when changed tp inverter drive.

    Of course, if your little fan is a bit sluggish, the the higher pulsed voltage may just “kick it up the you know what”, and get it turning.

    PWM or DC, does it matter? Maybe.

    Les.

    • This reply was modified 3 weeks, 4 days ago by Les.. Reason: Added phrase plus one sp
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    #38289

    Wheels-Of-Fire
    Participant
    @grahamdearsley
    Forumite Points: 4,072

    https://en.m.wikipedia.org/wiki/Computer_fan_control

    Just about all there is to know about PC motherboard fan control above ๐Ÿ˜

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    #38291

    keith with the teef
    Participant
    @thinktank
    Forumite Points: 2,217

    Good luck with the fans Dave. They will soak up some time configuring. Is that a Dyson vacume cleaner I can feel blowing around my ancles? No it’s the new build pooter thats trying to fly. ๐Ÿ™‚

    Oh, and a photo if you can.

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    #38296

    Bob Williams
    Participant
    @bullstuff2
    Forumite Points: 5,729

    On the subject of fans: I have a boxful of the damned things, legacy of my hoarders brain, never could chuck stuff away until recently. 120’s and 140’s: anyone wants one I’ll make a list. P&P only wanted. Lots of mounting screws, 4 with every fan.

    I’m a Magpie!

    • This reply was modified 3 weeks, 4 days ago by Bob Williams.

    If itโ€™s the Psychic Network why do they need a phone number?

    Whatโ€™s right is whatโ€™s left if you do everything else wrong.

    If women ran the world we wouldnโ€™t have wars, just intense negotiations every 28 days.
    --- Robin Williams

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    #38300

    Dave Rice
    Moderator
    @ricedg
    Forumite Points: 4,183

    It’s built, software later.

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    #38314

    Dave Rice
    Moderator
    @ricedg
    Forumite Points: 4,183

    Windows 1909 installed spectacularly quickly. Got all the basic utilities on then installed StoreMI.

    As you can see from the pic below it appears to set up a 3rd drive which is the sum total of the two real drives and this is what Windows writes to. StoreMI then decides if a particular block needs to be fast or slow. I also set up the 2GB memory cache, with 16GB available it seemed daft not to.

    So far it does what it says on the tin, but as everything was on the NVMe drive (the HDD had to be blank) it’s no faster, but then it’s not slower either ๐Ÿ˜€

    The real test will come when he downloads his Steam library, that will be more than the NVMe could handle on it’s own.

    As expected this PC is very quick to boot and snappy in use. I’ve come to expect no less now even with the cheaper CPUs like the 200GE or 2200G. These “quad” CPUs have more than enough grunt to get Windows up and running and with 8GB+ and an NVMe boot drive they just fly.

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    #38316

    keith with the teef
    Participant
    @thinktank
    Forumite Points: 2,217

    Nice Build. Yes NVMe drives are brill and nutsly fast. Think I will give the storeMI a go. ๐Ÿ™‚

    Thats good ram you got there.

    If you fancy tweaking your case fans then I use DC for system teperature @1/35c, 2/40c, 3/45c and 4@ 50 centigrade with fan speed set @ 1/600RPM, 2/ 840, 3/960 and 4 @ 1200 RPM. .

    Good Photos. Nice work shop. You must of had yer jumper on. ๐Ÿ™‚

     

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    #38320

    Wheels-Of-Fire
    Participant
    @grahamdearsley
    Forumite Points: 4,072

    My case has fan mounts galore, 2 in the back, 3 in the roof, 2 in the front, 1 in the floor, 2 on the left side and 1 on the right BUT I only fit 3 fans. I have tried fitting more but it never seems to make any difference.

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    #38322

    Bob Williams
    Participant
    @bullstuff2
    Forumite Points: 5,729

    Graham I came to that same conclusion when I rebuilt this desktop. 1 on floor, 2 at top, 2 fronts, 2 at side, 1 rear. I got down to 2x front (140mm), 1x top (120mm), 1x rear (120mm)

    Kept taking out fans, running system to warm, checking with CPUID Hardware Monitor.ย  Took a long time, but I finally wound up with optimum. I think that mounting too many fans can lead to what I christen “crosswind conflicts” in the case. Wind shear is another description, borrowed from aircraft and rifle days. At different heights, winds can blow at different speeds and directions. Can play havoc with aircraft and distance shooting, has to be calculated. In aircraft that’s done by computers (not always correctly, hello Boeing!) but a sniper has to study ground, air temp, look for bird flight, cloud movement, vegetation movement, etc. I am told that this is done by a device now. Cheating! I can still look at a bird at height and judge if the wind up there is blowing in a different direction to me down here. IF I have the right specs on, lol!

    All I know is that my system temps are OK with my fan setup. Nothing goes over 29ยบc.

    • This reply was modified 3 weeks, 3 days ago by Bob Williams.

    If itโ€™s the Psychic Network why do they need a phone number?

    Whatโ€™s right is whatโ€™s left if you do everything else wrong.

    If women ran the world we wouldnโ€™t have wars, just intense negotiations every 28 days.
    --- Robin Williams

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    #38349

    keith with the teef
    Participant
    @thinktank
    Forumite Points: 2,217

    I made the observation that for the first time with bios 1004B that I can overclock my ram. It is now a@ 14,16,16,16 3200Mhz and the default was 16,18,18,18 3200, so well pleased. It was pointed out on tech spot that if the VRM get to hot then the CPU will underclocked. So I will look into that ata the week end. ๐Ÿ™‚

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    #38351

    Wheels-Of-Fire
    Participant
    @grahamdearsley
    Forumite Points: 4,072

    I would be interested to know if that made any difference to your benchmark’s Keith ๐Ÿค”

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    #38352

    keith with the teef
    Participant
    @thinktank
    Forumite Points: 2,217

    @WOFY. ๐Ÿ™‚ So Tech spot recon that if you are not GPU bound then overclocking your ram will increase fps. Lol but its one of them isnt it. For the most part we are GPU bound and when we are not we do not need extra FPS. ๐Ÿ™‚

    Oh btw I had to clockย  back down to 15,16,16,16, 3200. Unstable. PC ran around kicking in chairs and knocking down tables in a resturant in a west end town. ๐Ÿ™‚

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    #38354

    Wheels-Of-Fire
    Participant
    @grahamdearsley
    Forumite Points: 4,072

    A dead end world then ๐Ÿ˜

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    #38380

    keith with the teef
    Participant
    @thinktank
    Forumite Points: 2,217

    So. Tech spot are of the opininon. That with ryzen processors that if the VRM temperature hits 100C and above then the CPU will start to throttle back.

    Damn.

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    #38388

    Wheels-Of-Fire
    Participant
    @grahamdearsley
    Forumite Points: 4,072

    Have you got a PWR fan header on your MoBo ? Its ment for cooling the VRM’s. I never have a problem with my VRM temp so I have mine set to constant speed and it drives the fan in the roof of my case because its the only header the short fan lead will reach. I ment to get a lead extension at some point but its been like that for 8 years now ๐Ÿ˜

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    #38394

    keith with the teef
    Participant
    @thinktank
    Forumite Points: 2,217

    I to also have no problems with VRM temps. As they sit next to the CPU cooler and have there own heat sink and so run 20c ish cooler than the CPU.

    But Damn 100C is mad hot in the first place. ๐Ÿ™‚

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