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  • Athlon II Passive cooling?

    Hi everyone. I'm building a media center with the following components:
    Motherboard: ASUS M4A785T-M
    CPU: AMD Athlon II 235e (TDP 45W)
    RAM: 2x 2 Gb kingston 1066 Mhz DDR3
    Case: Antec New Solution NSK2480 -EC

    In order to get a quiet system, I would like to limit the number of fans (especially smaller ones which are louder). So I wonder if I can use the stock Phenom II 940 heatsink I have (without fan) to cool the CPU. The case has two 12 cm fans, which should create a good airflow. Also the box won't have an hard disk (PXE boot).
    Is this possible? May it damage the CPU?

    Thanks in advance

  • #2
    My guess is that it should work, but there's no way to be sure except if you try out.
    Your CPU will definitely not get damaged (at least not immediately), as it's going to clock itself down automatically when the temperature gets critical.
    Just monitor the temperature with lm-sensors, if it stays below 60C under load you should be safe (more is probably ok as well, but I start to feel uncomfortable with more than that).

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    • #3
      Thanks! I'll try as soon as I receive the last pieces and post here.

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      • #4
        If possible, undervolt the Athlon; current AMD procs come with higher voltages than required to run, and so generate more heat than necessary.

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        • #5
          SPCR is a good site.
          http://www.silentpcreview.com/forums/

          Comment


          • #6
            Originally posted by kbios View Post
            Hi everyone. I'm building a media center with the following components:
            Motherboard: ASUS M4A785T-M
            CPU: AMD Athlon II 235e (TDP 45W)
            RAM: 2x 2 Gb kingston 1066 Mhz DDR3
            Case: Antec New Solution NSK2480 -EC

            In order to get a quiet system, I would like to limit the number of fans (especially smaller ones which are louder). So I wonder if I can use the stock Phenom II 940 heatsink I have (without fan) to cool the CPU. The case has two 12 cm fans, which should create a good airflow. Also the box won't have an hard disk (PXE boot).
            Is this possible? May it damage the CPU?

            Thanks in advance

            Hello

            I have an 45W TDP 4850e (the predecessor I'd say) and I have all besides the PSU and 2 ultrasilent casefans passively cooled. The CPU, the Radeon HD 3870 passively, the mainbaord chips. It is possible.

            I use the BTF-95 cooler (Butterfly, copper, looks nice and is still affordable). The cooler was also specified for much warmer (more TDP) CPUs at that time. It had a broad socket compatibility, came with mounting equipment for AMDs as well as intels. Installation was okay, though it needs some space.
            B.t.w. it is cold as ice on top. Even during compiling it stays cool (but the 4850e isn't a real hothead anyway). When I touch it now (during idling most of the time) the top feels like room temperature.
            So there are reserves left.

            look here
            www.zerotherm.net/eng/product/BTF95.asp
            I guess that one should also be able to cool a 65W TDP Athlon2.

            If you already have one that can cool a Phenom it should also be able to handle an Athlon.

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            • #7
              @all: thanks for your replies!

              @curaga: thanks; however I've read somewhere that heavy undervolting may kill the CPU. Do you thing it is safe to try 1.2 - 1.15 V?

              @Adarion: thanks, but I'm already far out of budget, so I would try not to buy anything else. In the worst case, I'll keep the Phenom heatsink with a fan, which should be quieter than Athlon's one.
              Last edited by kbios; 01-26-2010, 09:28 AM.

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              • #8
                1.25 should be on the safe side, enough to run any Athlon II IMHO. Lower might work, but would need testing to be sure.

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                • #9
                  I'm pretty sure you can't really kill a cpu by undervolting. You will start getting errors and crashes if you go to low though.

                  You could probably also use software fan control via fancontrol to shut down the fan completely below a certain temperature.

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                  • #10
                    http://www.lostcircuits.com/forum/vi...3&t=2703#p4963

                    Okay I've found it. I really don't know...

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                    • #11
                      Originally posted by chefkoch View Post
                      I'm pretty sure you can't really kill a cpu by undervolting. You will start getting errors and crashes if you go to low though.
                      Yep. It should not harm anything. The voltage the CPU is made/specified for is the Voltage where it is guaranteed by the mfg. that all transistors will shift and switch around. If you lower the voltage the power consumption will drop (I forgot the damn formula with frq. and voltage), without a loss of computing power. What can happen is, that not all transistors will switch and so you will get more or less severe errors. It is a matter of experiment but one should try to set the lowest specified voltage in every case, that should be safe. If your own CPU was produced on a nice day you might be able to go lower, if it was produced on a rainy monday... well. Not much capacity in undervolting.

                      Please note that not all BIOSes are genius and so if your box hangs after underclocking or undvervolting (or over~) you will have to reset the BIOS/CMOS by jumper so it will forget the settings a go back to failsafe defaults.
                      Some errors will not happen during P.O.S.T. but later when the OS kicks in or if you just stress your CPU. Then you can enter your BIOS setup and regulate the setings back to a safe position.

                      more on topic: @ kbios
                      If you ever happen to have some spare money, that thing was 35 Euros, in case you live e.g. in the US it should be cheaper (all electronics is more expensive in Europe, don't ask me why).
                      Though the boxed coolers aren't that noisy, esp. when you put them to a regulated fan port so it will regulate fan speed according to the temp. sensors. And a phenom cooler should always have the capacity for Athlons.

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                      • #12
                        Originally posted by kbios View Post
                        http://www.lostcircuits.com/forum/vi...3&t=2703#p4963

                        Okay I've found it. I really don't know...
                        Ouch: looks like the undervolted IMC state machine is getting confused and committing suicide.

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                        • #13
                          Wow.. that's new to me. I take that back then.

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                          • #14
                            Originally posted by chefkoch View Post
                            Wow.. that's new to me. I take that back then.
                            News to me too, and I used to work for a company that built chips with IMCs .

                            Comment


                            • #15
                              One should not write long post b4 seeing what other might have posted meantime. :/
                              Umm, that sounds really strange that they damaged the IMC. I would not expected that to have happened. Dead IMC p.o.s.t. code. Uh, sound horrible. Just some beeps and a number maybe and then it's over. Maybe someone from AMD could shed some light on it how to damage something by undervolting? Or on this "current sink" thesis from the thread?

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