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DELL Precision 490 Motherboard RAM issue

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    DELL Precision 490 Motherboard RAM issue

    Hello,
    I have 8 populated slots of ram for a total of 32GB but I have a problem on the amount seen from the system.
    I found this issue time ago when I seen that the boot sequence told me the amount of ram was changed and maybe in the next boot all was ok.
    Now the problem is always present and looking closer the mainboard I have seen 3 swollen 2200uF 6.3V capacitor around ram slots.
    It s possible that the bad capacitors dont give the correct voltage to the ram slots and I see this problem?
    Which capacitors are good for this application? (usually I use cheap ones but for this mainboard I would like to put good ones)

    This are good enough?

    Nichicon UHN1A222MHD6TO 10v 2200uf Radial Electrolytic Capacitor OLB024

    bye

    #2
    Re: DELL Precision 490 Motherboard RAM issue

    Yes they should be good enough but are likely old stock since they have been out of production for years AFAIK.
    I am not sure it will solve your issue though, it may be that one or several DIMM's have failed just as well...
    "The one who says it cannot be done should never interrupt the one who is doing it."

    Comment


      #3
      Re: DELL Precision 490 Motherboard RAM issue

      Caps could be the problem, they have to be replaced anyway. Also FB-DIMMs do take a lot of power and generate a lot of heat (they easily get above 60°C), and there are 8 of them, so make sure you use good 105°C rated caps.
      Otherwise old systems tend to develop bad contact in RAM (and PCI) slots so you can try to clean the RAM slots and DIMM contacts as well.
      OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

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        #4
        Re: DELL Precision 490 Motherboard RAM issue

        Maybe Sanyo 2200uF 16V could be better?
        Or Panasonic 2200uF 6.3V FR series EEUFR0J222?
        Last edited by kalauzz; 11-13-2020, 04:22 PM.

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          #5
          Re: DELL Precision 490 Motherboard RAM issue

          what are the dimensions of the original failed swollen 2200uF 6.3v caps? 10x20mm? if so, then yea the panny fr 2200uF 6.3v caps should work and fit fine as they are 10x20mm in size as well.

          Comment


            #6
            Re: DELL Precision 490 Motherboard RAM issue

            Originally posted by kalauzz View Post
            Maybe Sanyo 2200uF 16V could be better?
            Depends which series they are... but if they are the WF series, I strongly suggest to stay away from those. This is why:
            https://www.badcaps.net/forum/showth...98#post1000498

            On the other hand, the WG series may not be adequate enough for the application, or barely just enough.

            Also, Sanyo capacitors are now under the name of Suncon. So if those caps are indeed Sanyo, they are probably either old stock or counterfeit. In fact, counterfeit Sanyo capacitors were very popular on online sites at one point. Thus, my advice for them has been to generally stay away from Sanyo, unless the source can be verified to sell genuine Japanese caps.

            Originally posted by kalauzz View Post
            Or Panasonic 2200uF 6.3V FR series EEUFR0J222?
            Given the heat of FBDIMs as piernov mention, FR might actually be a decent choice. Just measure the old caps as ChaosL suggested, because otherwise your new caps may not fit on the board if they are physically bigger (typically their diameter and lead spacing.)
            Last edited by momaka; 11-14-2020, 09:36 PM.

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              #7
              Re: DELL Precision 490 Motherboard RAM issue

              Definitely replace any capacitor that is bulging. Recently I replaced one bulging capacitor near RAM and after that I was able to add two additional RAM sticks which previously made the PC freeze on boot every time with that bulged cap.

              Find datasheet for the current capacitors and get new ones with properties as similar as possible. You can go a little higher in capacitance but not lower. Make sure rated ripple is similar, can be higher. Impedance can be lower. Similar dimensions as well. Voltages on a motherboard are usually 3.3V, 5V, 12V. If a cap is 10V, most likely it's subjected to 5V, so you could replace a 10V capacitor with 6.3V, which is what I did with my bulging one. In fact the one I replaced was very similar to yours, a Nichicon HM 2200uF 10V, I replaced it with Panasonic FM 2200uF 6.3V.

              And of course, don't use random capacitors brands, use known ones like Panasonic, Nichicon, Suncon.
              Last edited by ribcage; 11-17-2020, 05:49 AM.

              Comment


                #8
                Re: DELL Precision 490 Motherboard RAM issue

                Originally posted by ribcage View Post
                You can go a little higher in capacitance but not lower.
                Actually, a lot of times, you CAN get away with slightly lower capacitance just fine: for example, 820 uF caps instead of 1000 uF. Generally speaking, going 20% higher or lower in capacitance shouldn't break the circuit. Of course, it is always better to go slightly higher than slightly lower, if you ever had to make that choice. And if you really had no choice and have caps that are something like 1.5x to 2x higher capacitance than the originals... chances are, those would still work fine - if you can get them to fit, of course.

                Same applies with ESR. In fact, ESR you can probably deviate as far as 30-40% of whatever the original was. Only on very marginally designed circuits, this may cause an issue (or if you were overclocking and really pushing hardware to its limits, making every bit of filtering count... which is probably not a great idea to begin with, but worth mentioning anyways.)

                Originally posted by ribcage View Post
                Voltages on a motherboard are usually 3.3V, 5V, 12V.
                That would be only for some of the caps near the PCI/PCI-E/AGP slots and on the input of buck VRMs and linear regulators. You will also find a lot of caps have even less than 3.3V on them (typically RAM V_dd, RAM V_tt, CPU V_tt, NB/SB/MCP Vcc and Vdd rails, and etc.) For these, even 4V polymer caps can be used sometimes. But always check first what the old caps are connected to (or measure voltages on them.) If unsure, just use 6.3V or 10V caps if the original caps were 6.3V or 10V. Bigger-sized 16V caps are generally on the 12V rail so will likely need to be replaced with 16V caps (but again, you can check and use lower voltage if you determine that is not the case.)
                Last edited by momaka; 11-20-2020, 10:46 PM.

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                  #9
                  Re: DELL Precision 490 Motherboard RAM issue

                  Thank you all for these explanations. I will put some Panasonic FR 1000uF 6.3v (exactly the same size d10x20mm.
                  Anyway I think I have some problems with contacts too.
                  Yesterday reseating dimm modules I increased usable ram size from 8 to 32GB.
                  In Bios before was 32GB installed but 8 usable.
                  In bios after reseating was 32GB usable (in quad channel configuration...faster!!)
                  I don’t understand why bios see always 32GB because this means stick are correctly recognized.
                  How can I clean ram sticks contacts ? And slots?

                  Regards

                  Comment


                    #10
                    Re: DELL Precision 490 Motherboard RAM issue

                    For contacts on RAM sticks - use pencil eraser to clean until shiny again. After this, wipe with IPA to remove any possible leftover rubber residue.

                    For RAM slots: IPA and toothbrush may help... or it may not.

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                      #11
                      Re: DELL Precision 490 Motherboard RAM issue

                      Hello,
                      I made replaced the 3 swollen caps somehow and the memory issue (for now) seems to be solved.
                      Anyway I had huge problems desoldering the old ones ( probably my desoldering tool is crap for this works, and my soldering iron too).
                      Eventually I ripped off old caps and soldered new ones on the old caps legs . I know this is really a bad way to work but I had no more way to proceed.

                      thanks to all

                      Comment


                        #12
                        Re: DELL Precision 490 Motherboard RAM issue

                        Originally posted by kalauzz View Post
                        Eventually I ripped off old caps and soldered new ones on the old caps legs . I know this is really a bad way to work but I had no more way to proceed.
                        That's OK. As long as you soldered the new caps well on there and preferably with as short leads as possible. But more importantly, make sure electrolyte didn't leak from the old caps on the board when you ripped out their leads - if it did, you should clean the affected areas with IPA as soon as possible. Otherwise, the traces on the board may get damaged from the electrolyte.

                        Comment


                          #13
                          Re: DELL Precision 490 Motherboard RAM issue

                          Yes , should be clean from electrolyte .
                          It was like an emergency solution because this is my main pc and I should make it works as fast as possible. Maybe with the right tools I can consider to redo the job better.
                          This experience made me consider to upgrade my soldering tool but I' m quite confused beetween all the offers on the market. I know its a personal choice but have you any good hint for buying a good soldering iron with a reasonable price.
                          Theoretically which wattage range is required to desolder hard motherboard capacitors.

                          By the way the ram quantity is still ok on 32gb since the capacitor replacing... new life for this old workhorse.

                          Regards
                          Last edited by kalauzz; 11-30-2020, 04:26 AM.

                          Comment


                            #14
                            Re: DELL Precision 490 Motherboard RAM issue

                            Originally posted by kalauzz View Post
                            This experience made me consider to upgrade my soldering tool but I' m quite confused beetween all the offers on the market. I know its a personal choice but have you any good hint for buying a good soldering iron with a reasonable price.
                            Theoretically which wattage range is required to desolder hard motherboard capacitors.
                            For soldering iron / station, I highly recommend going with T12 tip design. T12 tips have the heating element built into the tip, so they have better thermal response. For motherboard caps, I think you will probably want 50 Watts or more... but definitely temperature regulated, because otherwise above 40 Watts, regular wall-type irons tend to run very hot and burn through their tips fast.

                            With that said, if you want a station as cheap as possible, something like this should do:
                            https://www.ebay.com/itm/Quicko-T12-.../184427956876?
                            Note that it's just the station and doesn't come with a power supply. You will need to provide your own PSU / power brick. Generally, a 20V, 65 Watt laptop power adapter should work... though if you have a 24V, 4-6 Amp PSU available, that would be better and should allow the T12 tips to output higher power (when needed.) Also, same station above can also be found on AliExpress and other e-commerce websites. I think there is also a version with a power supply built-in... this one:
                            https://www.aliexpress.com/item/3280...archweb201603_
                            Personally, though, I'm not a big fan of the built-in power supplies, because they come with crap caps and you will eventually want to replace those too. So if you have a good quality laptop power adapter, you're better off using that instead.

                            Comment


                              #15
                              Re: DELL Precision 490 Motherboard RAM issue

                              Hello,
                              I bought a Hakko fx-888d, hope will be a good choice for my "value" equipments.

                              Best Regards

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