Announcement

Collapse
No announcement yet.

Asus CUV4-X suddenly has coil whine

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Asus CUV4-X suddenly has coil whine

    Hi,

    I've a CUV4-X motherboard for that I didn't use for some weeks, I wanted to reinstall it so put it in it's case again last week, after powering it up I noticed it had 'coil whine'. When I remove the videocard the noise is gone, tried 2 videocards same results. I've used the board for years and this is the first time it has this annoying sound. I tried two PSU's but same results, I'm 100% sure it's coming from the motherboard just not sure which location.

    Here is a picture of the motherboard http://hw-museum.cz/mb/46/asus-cuv4x

    Take a look at the first picture, bottom right (near the memory slots) - I noticed that coil (or choke or inductor don't know how to call it) is VERY hot to the touch (like I can touch it for 2 seconds then my finger 'burns'), other ones are cool. This is after 10 seconds after powering the PC on and sitting in BIOS. Is this normal? I have no idea if it was always so hot to the touch, might have something to do with the high pitched sound? Anyway I never replaced any caps on the board, but they all look OK, the ones near that hot coil do feel kind of warm to the touch though, probably because that coil is heating them up.

    Any thoughts?

    #2
    Re: Asus CUV4-X suddenly has coil whine

    I couldn't access the page to view the photo but you can look for ant fractured solder joints on hear sinks, coils, etc. The fans could be causing the whine sound, too.

    Comment


      #3
      Re: Asus CUV4-X suddenly has coil whine

      could be a coil resonating because the power is unstable,
      and that could be caused by a bad cap not smoothing the power to the video-card enough.

      Comment


        #4
        Re: Asus CUV4-X suddenly has coil whine

        What brand of capacitors does your motherboard use? The ones pictured at hw-museum.cz are Rubycon. But knowing ASUS, it's possible they could have used something else on your motherboard, so that's why I ask.

        If yours are Rubycon too, then they are probably still okay, despite being a tad old. Though if you do have an ESR meter, it won't hurt to pull a few and check them anyways. I pulled some caps a few days ago that looked "okay" but were actually bad (low capacitance, high ESR, etc.) These were OST and Ltec brand, so of course I don't expect the same from Rubycon... but again, it just doesn't hurt to check them if you can.

        By the way, the coil you see there on the bottom right of the picture you pointed - that's likely for the RAM supply (and seeing this is SDRAM board, the output of the coil should have 3.3V).

        As to why you only get coil whine when there is an AGP card... that I am not sure.
        The AGP termination voltage (3.3V, 1.5V, or 0.8V, depending on version, with AGP 1.0 running at 3.3V) is likely generated by Q16 - a TO-267 MOSFET by the AGP connector. So the two shouldn't be related.

        But if that coil gets hot within seconds of turning On the PC, I would suspect something is wrong in the circuit it is in. It's part of a buck-converter circuit and should technically be a lot more efficient than a linear regulator circuit (hence, much less heat). Generally, it's not uncommon on new motherboards to have hot coils - but loads nowadays are a lot more demanding than before (especially CPUs).

        The only thing I can think of is if the system is handling resources/IRQs differently with a video card, and perhaps putting more stress on the RAM somehow. And if the buck-circuit is marginal for whatever reason, that could be making the coil to heat.

        Do you have a PCI card you can test the PC with? Do you still get coil whine with a PCI video card? Does the coil still get hot?
        Last edited by momaka; 10-18-2018, 09:44 PM.

        Comment


          #5
          Re: Asus CUV4-X suddenly has coil whine

          Thanks guys.

          Originally posted by momaka
          What brand of capacitors does your motherboard use? The ones pictured at hw-museum.cz are Rubycon. But knowing ASUS, it's possible they could have used something else on your motherboard, so that's why I ask.
          They're the same, Rubicon.

          Originally posted by momaka
          By the way, the coil you see there on the bottom right of the picture you pointed - that's likely for the RAM supply (and seeing this is SDRAM board, the output of the coil should have 3.3V).
          Ah, that makes sense! I tried a BIOS Reset to revert any BIOS options I may have chosen that might affect the RAM. Didn't work though.

          Originally posted by momaka
          But if that coil gets hot within seconds of turning On the PC, I would suspect something is wrong in the circuit it is in. It's part of a buck-converter circuit and should technically be a lot more efficient than a linear regulator circuit (hence, much less heat). Generally, it's not uncommon on new motherboards to have hot coils - but loads nowadays are a lot more demanding than before (especially CPUs).
          Well I had another look today and it takes about 30 seconds for it to become really hot. Holding down the reset button alters the 'whine' sound. When picture is again sent to the PC, it starts to whine louder. Also going to the BIOS "Main" page increases the whine dramatically.
          The PC has no OS yet, so I've no idea if it get's worse in 3D mode or higher resolutions. It's probably bad for the motherboard to power it on with an AGP card now?

          Originally posted by momaka
          Do you have a PCI card you can test the PC with? Do you still get coil whine with a PCI video card? Does the coil still get hot?
          Great idea! I just tried one and there is no whine anymore, coil is now warm instead of hot.

          Comment


            #6
            Re: Asus CUV4-X suddenly has coil whine

            Originally posted by Justin1091 View Post
            Great idea! I just tried one and there is no whine anymore, coil is now warm instead of hot.
            Interesting...
            I still don't see the connection between the two, but there really must be one.

            That said, maybe see if the motherboard has options like "AGP Fast Write" and "AGP Aperture Size" in BIOS. Perhaps play with those and see if that changes anything.

            Originally posted by Justin1091 View Post
            It's probably bad for the motherboard to power it on with an AGP card now?
            Can't say for sure.
            How hot does the coil really get? Will it blister your skin? Or just hot enough to feel very uncomfortable for holding it for more than 1-2 seconds. If the latter, it's probably running around 60C - which is a little high indeed, but not unsafe by any means. Now when you have the coil windings hot enough to smell like burnt lacquer (I have a Corsair CX750M PSU with a hot-running output toroid inductor like that), then you have problems for sure.

            Discolored/darkened PCB is another indication that the coil has been running past 60C. In which case, it might just be a badly-designed VRM.

            I can tell you for a fact that quite a few late s478 to late s775 ASUS and AsRock boards had problems with hot-running RAM regulators, but these were of the linear type (i.e. only with a single MOSFET).
            Last edited by momaka; 10-21-2018, 10:42 PM.

            Comment


              #7
              Re: Asus CUV4-X suddenly has coil whine

              Originally posted by momaka View Post
              Interesting...
              I still don't see the connection between the two, but there really must be one.

              That said, maybe see if the motherboard has options like "AGP Fast Write" and "AGP Aperture Size" in BIOS. Perhaps play with those and see if that changes anything.
              Yeah it has these options, no effect after changing them though.

              Originally posted by momaka View Post
              How hot does the coil really get? Will it blister your skin? Or just hot enough to feel very uncomfortable for holding it for more than 1-2 seconds. If the latter, it's probably running around 60C - which is a little high indeed, but not unsafe by any means. Now when you have the coil windings hot enough to smell like burnt lacquer (I have a Corsair CX750M PSU with a hot-running output toroid inductor like that), then you have problems for sure.

              Discolored/darkened PCB is another indication that the coil has been running past 60C. In which case, it might just be a badly-designed VRM.

              I can tell you for a fact that quite a few late s478 to late s775 ASUS and AsRock boards had problems with hot-running RAM regulators, but these were of the linear type (i.e. only with a single MOSFET).
              Well I installed the OS yesterday with the pci card and installed it's drivers, coil still cool after an hour.
              Today I put the AGP card in along with the PCI card (monitor connected to PCI card): coil whine returned. When I connect the monitor to the AGP card it gets a lot louder.

              Anyway, had it run with the AGP card with its drivers installed for 2 minutes at the desktop, powered off the PC and touched the coil. Now it was so hot that I couldn't touch it for longer than 1 second. No smoke, burn marks or smell though. Also checked the other coils but those are all cold. Hot one cools down really fast though (within seconds) after turning the PC off.

              Comment


                #8
                Re: Asus CUV4-X suddenly has coil whine

                Ok just found out that C220 (near the screw hole) was shifted and loose. It came off very easily (no force applied!).
                I found it in the case but should I solder it back on or buy a replacement? No idea what type it is (ceramic?) I think it's brown.
                Maybe this is why the coil got so hot?

                Comment


                  #9
                  Re: Asus CUV4-X suddenly has coil whine

                  Measure it if you have a capacitance meter, if it measures as a capacitor then solder it back in.
                  "The one who says it cannot be done should never interrupt the one who is doing it."

                  Comment


                    #10
                    Re: Asus CUV4-X suddenly has coil whine

                    Originally posted by Justin1091 View Post
                    Ok just found out that C220 (near the screw hole) was shifted and loose. It came off very easily (no force applied!).
                    ...
                    Maybe this is why the coil got so hot?
                    Yes, could well be that.
                    U26 appears to be the buck-controller for the regulator circuit that this coil is part of. So you definitely need to have that cap back in there.

                    I would take Per Hansson's advice: if you have a capacitance meter, check the capacitance of the original cap. If it measures good capacitance (probably a few hundred nanoFarads to 1-2 uF, I'd guess), you can solder it back in. But if you can't read any capacitance on it, check it for short-circuit or low-resistance with your multimeter (chipped and broken ceramic caps can become short-circuited). If bad, then you can look for replacement. For that however, we might need to know what U26 controller is so that we can figure out what value we need (or what range of values would work there).

                    Comment


                      #11
                      Re: Asus CUV4-X suddenly has coil whine

                      Thanks a lot guys, close to solving it then probably!

                      ATM I don't have my multimeter with me but I will check the capacitor and post back results in a day or two.

                      Attached is picture of how the capacitor looked and U26 sheet.

                      I'm curious, aside from the coil probably heating when this capacitor is not in, what else happens? Other parts get too much power and degrade faster?
                      Attached Files

                      Comment


                        #12
                        Re: Asus CUV4-X suddenly has coil whine

                        Originally posted by Justin1091 View Post
                        Thanks a lot guys, close to solving it then probably!
                        ...
                        I'm curious, aside from the coil probably heating when this capacitor is not in, what else happens? Other parts get too much power and degrade faster?
                        Well, this capacitor appear to be part of the compensation network between pins 4 and 5 (COMP and FB, respectively) of U26. The compensation network basically makes sure the buck regulator runs smoothly at all loads. So with that cap missing, it's possible to make the feedback loop unstable at certain loads, and thus the voltage output of that buck regulator could have been unstable and/or oscillating - hence why the coil was heating up.

                        That said, it's unlikely that anything else got degraded/damaged. At worst, the coil's core lifespan might have decreased a little, along with the caps connected to it (since they probably got hot too). But again, sounds like it wasn't running to excessively hot. So it's probably okay. So all you have to do now is just really figure out the value of that capacitor, and all else should be okay.

                        Comment


                          #13
                          Re: Asus CUV4-X suddenly has coil whine

                          Originally posted by momaka View Post
                          Yes, could well be that.
                          U26 appears to be the buck-controller for the regulator circuit that this coil is part of. So you definitely need to have that cap back in there.

                          I would take Per Hansson's advice: if you have a capacitance meter, check the capacitance of the original cap. If it measures good capacitance (probably a few hundred nanoFarads to 1-2 uF, I'd guess), you can solder it back in. But if you can't read any capacitance on it, check it for short-circuit or low-resistance with your multimeter (chipped and broken ceramic caps can become short-circuited). If bad, then you can look for replacement. For that however, we might need to know what U26 controller is so that we can figure out what value we need (or what range of values would work there).
                          Well you were right, the capacitor was the cause. I measured it with a multimeter and decided to give it a try and solder it back. Pretty irritating to solder something so small

                          So, coil whine is gone and coil is *cold* after an hour of using the pc!

                          Thanks a lot to all of you for helping me out!

                          Comment


                            #14
                            Re: Asus CUV4-X suddenly has coil whine

                            No problems, glad to hear you got this one working.

                            Yeah, those small SMD caps and resistors seem annoying at first. But once you get used to them, they are not that bad (actually, I can do these quicker than through-hole components quite often). I do them with an oldschool 30-Watt Radio-Shack iron with copper tip shaped into a spoon shape. I usually keep this spoon-shaped tip filled with solder. So when I need to desolder (or solder) something small like that, I just put flux on the SMD component and touch it with the iron. In case of desoldering, I touch both sides at the same time. For soldering back on the board, I hold the component (with tweezers) and touch the iron on ones side, then the other.

                            Comment

                            Working...
                            X