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test of thermal pad on AMD

Discussion in 'AMD Thunderbird' started by Stacey, May 16, 2004.

  1. Stacey

    Stacey Guest

    Lots of talk here recently about thermal pads and what is better etc. I've
    seen big drops in temp's ditching the thermal pads and just using plain 'ol
    white HS compound instead. Others claim you'll only see a minor change
    so...

    I just bought a Barton 2500+ on a chaintech 7NIF2 board for by brother. It
    was a retail chip with a factory HSF. I just put it on as supplied and when
    I booted it up, the idle temp was right at 50C in the bios. Seemed kinda
    high but MBM5 said 40C so figured it was OK.

    After I got it all set up, the system was pretty noisy from the fans so
    wanted to try to quiet it down some. Removed the fan grills, added some
    10ohm 1W resistors to the case fan and PSU fan etc. Rechecked and the CPU
    temp was the same but now the CPU fan was the loudest one.

    So I took the factory HS off and removed the pad. It wasn't like intel's
    pad, more like a gooey piece of cheeze? Anyway removed the pad and sanded
    the bottom of the HS smooth, it was pretty rough and I know HS compound
    likes a smooth surface. The pad was so thick this didn't matter. After I
    reinstalled the HS with plain white compound, the idle temp was 11C less,
    down at 39C in the bios and 29C in MBM5. Now I could add a resistor to the
    CPU fan, drop the RPM 1000 RPM and still is cooler (43C) than it was with
    the pad and MUCH quieter!

    So anyone installing a retail AMD chip, my advice is to ditch the pad, sand
    the bottom of the HS on a piece of glass and throw on some white HS
    compound and stay cool/quiet.
     
    Stacey, May 16, 2004
    #1
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  2. Stacey

    Don Taylor Guest

    I've got the same but with ECS N2U400-A board. Room temp was 18C,
    BIOS said cpu was about 48C, no case fans, side off the case. I
    turned a big room fan against the open side of the case and it
    dropped to the lower 40's. Those are about the same as my AMD 2000
    with a Vantec TMD Aeroflow and the white goop.
    Instructions said mine was a phase change material, water clear,
    looked less than 1mm thick of rubber cement. Trying to get that
    clip on the heat sink latched down was impressive, Even with a
    screwdriver to apply pressure I couldn't get it to latch. Then
    someone banged on the door and I had to move the case. The heat
    sink fell off in the process. When I saw this the second time the
    material had changed to a dark grey looking material with a big
    impression in it where I had been applying all the pressure. I
    wasn't sure whether it was one-time-only or not but I went ahead
    and got up on the table with the screwdriver and REALLY applied the
    pressure, along with prying the edge of the clip to let it slip
    into place. Finally it popped on there.
    I didn't notice the bottom of the sink being rough. Maybe I just
    didn't look closely enough. What did you use for polishing compound?

    But I think I'm leaning in the direction of a big house fan that
    will be ducted to drive air through the cases.

    While I was doing all this, and listening to the old house fan
    roaring away, the house down the street caught fire. That reminded
    me of an old fan a friend and I had mounted in a window decades ago
    to pump the hot august air out of the house. The fan made a lot
    of noise and fortunately we happened to be in the kitchen looking
    at it when it went up in flames.

    Does anyone know of a relatively cheap smoke detector like device
    BUT it will switch off maybe 1000 watts of power when it thinks
    that something has caught fire? I'm surprised that there isn't
    something like that out there that I've seen. I'm really not wanting
    to come home some evening and discover that a fan failed, burned,
    and took the whole place with it.
     
    Don Taylor, May 16, 2004
    #2
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  3. What grit sandpaper did you use?
     
    sooky grumper, May 16, 2004
    #3
  4. Stacey

    Stacey Guest

    Started with 120, then 220 then 400. Put the sandpaper on some fairly thick
    glass to make sure it was flat. It doesn't have to be polished, just
    smooth.
     
    Stacey, May 16, 2004
    #4
  5. Stacey

    kony Guest

    You're right, the original TIM is horrible, but also consider that the
    original TIM may take several days to reach max efficiency, and heatsink
    surface may vary... none are what I'd call "great" but some a lot rougher
    than others. Everyone should get good results following your method but
    some may see less drop in temp than you did.
     
    kony, May 16, 2004
    #5
  6. Stacey

    ~misfit~ Guest

    Not a fair test. The pad needs a few days of hard work to heat up and
    squeeze out the excess material. If you'd run SETI for a week with the pad,
    checked temps, then tried goo it would have been valuable data, as it is,
    it's junk science.
     
    ~misfit~, May 17, 2004
    #6
  7. Stacey

    Stacey Guest


    It ran 24/7 for 2 days, how long does it need to run to -start- working
    right?

    BTW have you ever looked at the surface on the bottom of the newer HS's they
    give you in the retail box? Looks like it was surfaced with a 40 grit
    grinder.
     
    Stacey, May 17, 2004
    #7
  8. Stacey

    Clint Guest

    I did something similar with my Intel 2.4B processor. Before I lapped the
    stock HS, I checked it with a straight-edge, and there was a considerable
    concavity (is that a word) in the center of the HS. After lapping the HS,
    and replacing the TIM with Arctic Silver 3, the temps dropped by about 10
    degrees. This was on a unit that had been running for several weeks prior
    to my hacking around on it.

    Clint
     
    Clint, May 17, 2004
    #8
  9. I replaced a customers XP 1800+ with a 2200+ the other day and the cpu
    temp at idle went from 60C to 45C

    --
    -Luke-
    If cars had advanced at the same rate as Micr0$oft technology, they'd be
    flying by now.
    But who wants a car that crashes 8 times a day?
    Registered Linux User #345134
     
    beav AT wn DoT com DoT au, May 17, 2004
    #9
  10. Stacey

    Ben Pope Guest

    Cheap smoke alarm with a relay? Maybe you'd want some help with keeping the
    relay contacts connected - I suspect it would eat batteries. The other
    concern is of course fail safety... no point in having a battery open
    circuit the relay - when the battery runs out, it'll close again.

    Besides, if the thing is on fire, there seems little point in switching it
    off. Kind of a bit late?

    Ben
     
    Ben Pope, May 17, 2004
    #10
  11. Stacey

    ~Aart Guest

    amd's web site recommends pads, not grease.

    If grease is better, why are they recommending pads?
     
    ~Aart, May 17, 2004
    #11
  12. Stacey

    spodosaurus Guest

    Less likely to bugger it up with a simple pad...
     
    spodosaurus, May 17, 2004
    #12
  13. Stacey

    motts Guest

    I'm glad this topic came up. I wanted to ask all of you if you've
    ever seen a degadation in performance of AMD's thermal pads. I built
    an Athlon XP 2200 in April 2003 using the stock HSF and pad along with
    standard case fans and no overclocking, and it's been 24/7 ever since.

    A year ago the idle temp ranged between 30-40 deg C depending on the
    ambient room temp, and full sustained load temp of 47 at most. Now in
    the past month or two the idle temp tends to hang aroung 40-45 and the
    full load temp has gone up to 52.

    I cleaned out the case and HSF fins of dust multiple times and it
    didn't make a difference. The fan RPMs are still reporting 4000 rpm
    in the BIOS so I don't think it's the fan.

    Is there a limitation in the life of AMD's thermal pads? I have fears
    that it's thermal transfer properties are going to break down
    completely. Should I remove the HSF and pad, sand it smooth, and use
    some Artic Silver?

    Thanks for any comments.
     
    motts, May 17, 2004
    #13
  14. Stacey

    kony Guest

    Yes, if you suspect that the TIM isn't working effectively you "COULD"
    take the 'sink off, thoroughly clean off original pad material (petroleum
    solvet works well for this, but do not scrape with a metal object). If
    you then find the 'sink bottom to be rough you might mildly lap it with
    fine-grit sandpaper (at least 320 grit or finer for the final pass).

    If you lack any polishing compound then any generic thermal compound or
    especially arctic alumina will polish it up some... not as good as many
    polishing compounds, but "good enough", and the residue is even
    beneficial, doesn't need thoroughly cleaned off but if it remains in the
    tiny crevaces of the metal it's a GOOD thing.

    However, it is not necessary to use arctic silver. With a heatsink having
    a good surface the difference in using arctic silver isn't significant.

    On the other hand, a full load temp of 52C is not too hot, it should still
    be completely stable. There are also other reasons why the temp might
    read differently, for example a bios update can change the temp offset
    used by the bios and immediately show a temp difference similar to what
    you've seen. If you were overclocking it would be more of a concern but
    it may not be worth the bother to do anything at 52C.
     
    kony, May 17, 2004
    #14
  15. Stacey

    ~misfit~ Guest

    48 hour should be getting close, *if* it was under 100% load for that time,
    say, running Prime95. It's phase-change material, meaning it needs to get
    hot for a while to do it's thing.
    Yep, they're pretty rough alright.
     
    ~misfit~, May 17, 2004
    #15
  16. Stacey

    motts Guest

    Thanks for the response. Maybe I should leave it alone. I know that
    the 52 is not considered hot since AMD's spec sheets say 90 as a max,
    and the machine has always been completely stable. I was just
    concerned that the change is an indicator of pad breakdown and I'm
    scared that it will breakdown completely. I never updated the BIOS
    since there were no updates from the MB manufactuer in the past year.
    This is strictly some kind of breakdown occurring in the pad and/or
    HSF. I never touched the CPU/HSF after I built the machine, other
    than spraying air at it to blow out the dust from the fan blades and
    fins.

    I was at Fry's yesterday looking at new HSF assemblies and considering
    some of the simpler ones, but they are all so large that I'm not sure
    if they'll fit. The only way to test them is to actually install them
    and if it turns out they don't fit then I'll be forced to go back to
    the stock HSF and follow your procedure below.
     
    motts, May 17, 2004
    #16
  17. Stacey

    kony Guest

    If it's going to worry you or if you see a continual decline in thermal
    transfer, that is, ever-increasing temp, then it may be worthwhile to
    remove 'sink, lap and use compound just for that piece of mind. Although
    previously I wrote that Arctic Silver isn't necessary, there is a benefit
    to synthetic compounds in general, that in long term use on hot small CPU
    cores they tend to stay mixed, not separating so readily as silicone based
    compound can. Generally with a heatsink using silicone compound and a
    very hot CPU with such small core area (Athlon or Duron) I'd plan to
    reapply compound every 18 months or so, but certainly it depends how hot
    it gets... some of my boxes run full load for hours on end and certainly
    generate more heat than others.

    As for the Frys heatsinks, there are no Frys here and i"m not familiar
    with their selection but in general it's good to buy biggest 'sink that
    will fit, one that accepts an 80x25mm fan. Larger metal surface area
    (will an all copper bottom) allows lower CFM airflow, in conjunction with
    the large fan, can result in quieter operation, longer fan lifespan, and
    often a longer interval between cleaning.

    AMD designates what's called a "keep out zone", which is the area around
    the CPU socket in which manufacturer of motherboard should avoid placement
    of any components that interfere with heatsinks meeting same keep out zone
    specification. Generally most 'sinks do meet this, with notable exception
    of Thermalright SLK-900 and possibly others with wing-like fins, possibly
    the Zalmans also. A careful measurement of the board should determine if
    a 'sink will fit, you can get specs on the 'sink measurement at it's
    manufacturer's website or many online vendors. In some situations I'll
    get a 'sink knowing it's barely too big and simply take a hacksaw,
    grinder, or dremel tool to the conflicting area on the 'sink, as I really
    like to use biggest 'sink possible within reason, due to aforementioned
    benefit of allowing selection of optimal fan.

    Still, with your 'sink having degraded performance yet still keeping CPU
    at 52C, you should be content with that heatsink, there's no benefit to
    lower CPU temp unless you want to push the theoretical limits of CPU
    lifespan and try to use it for a couple decades or longer.
     
    kony, May 17, 2004
    #17
  18. Stacey

    Don Taylor Guest

    I was thinking that cutting off the power might help stop feeding the
    fire as the fan was going up in flames.

    I actually observed this happen with a house fan a few decades ago.
     
    Don Taylor, May 18, 2004
    #18
  19. Stacey

    kony Guest

    Why not just put a solenoid valve on a fire extinguisher and connect that
    to the fire alarm?
     
    kony, May 18, 2004
    #19
  20. Stacey

    Stacey Guest


    That's what it sounds like. I was shocked at how course the finish was on
    the HS, very little of the surface would ever touch the die prior to
    sanding it smooth. I'd guess it would work as well now with no thermal
    compound as it did with the original surface finish and their pad.
     
    Stacey, May 18, 2004
    #20
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