MP 1,1-5,1 CPU A runs hotter then CPU B

Discussion in 'Mac Pro' started by MrRedfield, Jul 18, 2019.

Tags:
  1. MrRedfield macrumors newbie

    Joined:
    Jul 8, 2019
    #1
    Hello,
    I just upgraded my processors to dual Xeon X5690's. It seems that CPU A is running about 10 degrees hotter than CPU B. Is this normal? Sadly, I never looked at the temps before upgrading the CPUs.

    Thanks!

    BTW. My system is a 5,1

    [​IMG]
     
  2. bjar macrumors regular

    Joined:
    Feb 20, 2013
    Location:
    Sugar land, tx
    #2
    Completely normal.
     
  3. tsialex macrumors 603

    tsialex

    Joined:
    Jun 13, 2016
    Location:
    Brazil
    #3
    It's normal. CPU B gets the cooler outside air, CPU A gets the already warmed air from CPU B. Most people delta is around 6ºC or 7ºC, but there are some reports of 4ºC to 11ºC.
     
  4. chrfr macrumors 604

    Joined:
    Jul 11, 2009
    #4
    my 12 core 2.66 is sitting here with about an 8ºC difference between the two. It's totally normal.
     
  5. MIKX macrumors 65816

    MIKX

    Joined:
    Dec 16, 2004
    Location:
    Japan
    #5
    My 4,1>5,1 has a 5°C difference. Normal.
    It would seem that increasing Exhaust fan speed might reduce the difference slightly.


    Off topic :
    I would love to learn how to wire up new Noctua Intake & Exhaust fans original Apple cables to work with Apple thermal sensing.

    Possible ? All ideas more than welcome !

    I have already bought ( for my PSU ) a Noctua 120MMx120 NF-A12x25 fan kit
    NF-A12x25 PSU 120mm fan kit.png

    . . . .along with the Noctua NA-FX1 fan controller fan kit
    Noctua Fan controller NA-FC1.jpg

    - I have both a passive thermal sensor along with a Laser Thermal gun to monitor PSU temps so I don't need Apple Thermal monitoring. Anything under 40°C for the PSU in summer will please me.
     
  6. startergo macrumors 65816

    startergo

    Joined:
    Sep 20, 2018
    #6
    This is normal. What is not normal is CPU B hotter than A. Which I have seen in the thread where people try redirecting the fan flow towards the Northbridge diode.
     
  7. Alex Sanders74 macrumors 6502

    Alex Sanders74

    Joined:
    Nov 26, 2013
    Location:
    Toronto, Canada
    #7
    Very curious how this works out for you. These kits are really nice and have been looking at them for a while now....
     
  8. MIKX, Jul 19, 2019
    Last edited: Jul 19, 2019

    MIKX macrumors 65816

    MIKX

    Joined:
    Dec 16, 2004
    Location:
    Japan
    #8
    EDITED :
    As it stands, the Intake fan & Booster A fan direct airflow to the 4 front RAM slots and seeing that the Northbridge is basically (EDIT) almost under CPU A then diverting said airflow to the Northbridge ' should ' give extra cooling to both the NB AND CPU A.

    Last April I tried the ' airflow diversion panel ' technique but the results were minimal, disappointing.

    Instead, I installed USB fans to address the Northbridge chip and it stays at around ( EDIT ) 55 ~ 58°C / around 136°F if ambient temp doesn't go over 35°C / 95°F. Admittedly my Intake & Exhaust fan speeds have been set a bit higher in summer.

    I also have a 16.4 CFM USB fan installed for the CPU A's front, four RAM slots, so I've got that covered for extra airflow.
     
  9. MIKX macrumors 65816

    MIKX

    Joined:
    Dec 16, 2004
    Location:
    Japan
    #9
    Bear in mind that my main plan is to use a Noctua PSU fan without Apple thermal control but as I posted before, I can easily monitor and control that.

    I'm going to contact Noctua regarding pinouts for their 80mm fans for the CPU Tray ( Intake & Exhaust ) to make them Apple thermal control compliant. It's all about the cable pinouts ( hopefully ).

    Seeing that there are still literally millions of working, aging cMPs out there it could be good for Noctua to come up with a "Mac Pro Noctua fan adaptor cable kit". It is certainly worth considering and their fans are excellent and well crafted.

    NOTE : The 4,1 & 5,1 's PSU fan cable runs UNDER the motherboard= a time consuming pain in the arse to remove.
    example :
     
  10. Alex Sanders74 macrumors 6502

    Alex Sanders74

    Joined:
    Nov 26, 2013
    Location:
    Toronto, Canada
    #10
    The thermal control aspect is what's deterred me from going further. Cable routing does sound like a royal pain... I'll keep my eyes open for what developments you discover on this front. Time and money are something I don't have a lot of to invest in this area right now. Appreciate your efforts!
     
  11. tsialex, Jul 19, 2019
    Last edited: Jul 19, 2019

    tsialex macrumors 603

    tsialex

    Joined:
    Jun 13, 2016
    Location:
    Brazil
    #11
    Mac Pro fan RPM measuring is completely different than what PC fans use and the signals are not compatible at all.

    If you connect an oscilloscope at the sense pin you will see that you can't replace a Mac Pro fan and make the SMC read the RPM of the PC PWM fan. Years ago a user here, sorry I don't remember who see edit below, did all the investigation needed and posted all the signal differences. You would need a micro controller to do the translation from one to the other. At the time seemed doable, but if no one did it already…

    You can use the +12V and ground from the Mac Pro connections, but you can't use the management.

    Edit: this post have more info about the difference between Delta fans used in the Mac Pro and common PWM PC fans:

    https://forums.macrumors.com/threads/quieter-case-fans.1115475/#post-12708222
     
  12. MIKX macrumors 65816

    MIKX

    Joined:
    Dec 16, 2004
    Location:
    Japan
    #12
    That Austrian ? guy's video is spot on - he is truly bi-lingual but I cringed when he picked up the CPU Tray by the heatsink ! Definitely a NO NO with 4,1 & 5,1's trays.

    CPU Tray by HAND.png

    At the moment, in my De-dusting & cooling the Northbridge epic, https://forums.macrumors.com/thread...mp-reduction-in-dual-cpu-cmp-4-1-5-1.2179729/ the PSU temps are the only thing that concerns me, especially as I'm in humid, fiercely hot Japan. Yet due to Climate Change JP's Summer has been peaking about two weeks earlier since I first arrived here in 1994.

    I'll report any developments re: CPU Tray area Intake & Exhaust fans.
     
  13. Alex Sanders74 macrumors 6502

    Alex Sanders74

    Joined:
    Nov 26, 2013
    Location:
    Toronto, Canada
    #13
    That heatsink makes a great carry handle! :eek:
     

Share This Page

12 July 18, 2019