Mac Pro 5,1 Expansion Slots Fan speed faster than expected

Discussion in 'Mac Pro' started by vasuvasu, Jun 11, 2016.

  1. vasuvasu macrumors member

    Aug 8, 2011
    Bought a used 5,1 and just did an upgrade from dual 2.4ghz quad to dual 2.4ghz six-core (x5690) CPUs. Post upgrade, the new chips seem to be running as hot as everyone elses (40ºC-84ºC), so nothing out of the ordinary there.

    With the stock ATI 5770 (1 power cable) that it came with, everything is quiet as can be, but as soon as I put in my MVC Nvidia GTX 570 (2 power cables), the machine gets a little louder. I notice the Expansion Slots fan and the Power Supply fan ramp up in speed.

    The Expansion Slots fan speed went up to around 1600rpm and the Power Supply fan went up to 1100rpm and stayed there for about half an hour. For whatever reason, the speeds came down on their own. The Power Supply fan is now sitting comfortably at 600rpm, and while the Expansion Slots fan speed came down, it's still running at around 1000rpm without any load on the machine (machine booted up to Finder, no apps or benchmarks running). Comparatively the Expansion Slots Fan with the ATI 5770 was just 800rpm.

    Is this normal? I know 1000rpm isn't much more than 800rpm, but it's just enough for me to hear them, especially when I do something a little graphically taxing and there's more GPU demand. This card and my 3,1 Mac Pro were always whisper quiet, so I'm not sure what's going on differently with the same card in the 5,1 to make the Expansion Slot fan run a little harder. Anyone have any ideas?
  2. MultiFinder17 macrumors 68000


    Jan 8, 2008
    Tampa, Florida
    It's a beefier GPU that produces more heat and draws a bit more power. It's to be expected that the fans would run a tad faster.
  3. vasuvasu thread starter macrumors member

    Aug 8, 2011
    I've been using this card for 5 years in my 2008 Mac Pro and it never made any of its fans run faster though :(
  4. Synchro3, Jun 12, 2016
    Last edited: Jun 12, 2016

    Synchro3 macrumors 68000


    Jan 12, 2014
  5. h9826790 macrumors G4


    Apr 3, 2014
    Hong Kong
    4 options here.

    1) ditch that card (for nothing), so, not a good option.

    2) run anything that can stress the GPU (most GPU benchmark will do, including CUDA-Z). This may be a bit annoying, but work.

    3) keep resetting the SMC, less than 50% chance can fix the problem temporarily. A bit waste of time.

    4) use MacsFanControl to manually make a profile for the PCIe fan (e.g. Base on PCIe ambient), and PSU fan (e.g. Base on PSU component temperature). You only need to do the setting once, and fully automatically in he future. Protential threat, wrong setting and make the fan run too slow, so cause the PSU pre- mature failure.

    I am now using option 4, very happy with that. In fact, both my PCIe and PSU fans are now base on temperature, but not power draw. Which makes them run cooler in the summer time, and quieter in winter.
  6. vasuvasu thread starter macrumors member

    Aug 8, 2011
    Awesome, thanks for the responses! I'm also hoping to replace the GTX 570 I have now which uses upwards of 236 watts with with a Maxwell or Pascal card which uses much less power.

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