MacPro 1,1 upgraded CPU freakishly low temp

Discussion in 'Mac Pro' started by macagain, Dec 11, 2011.

  1. macagain macrumors regular


    Jan 1, 2002
    I just upgrade my 2006 1,1 with a pair of E5345's (2.33 quad). It runs like a charm.

    However, the CPU temps as displayed by iStat menus seem to go down as CPU usage goes up! It does add up in my mind! It normally idles around 50-55 C. On a handbrake run, with all CPUS at or near 100%, the temps go down to around 20C! After awhile, as the temps go down even more, the fans do speed up just a bit.

    Does this make sense to anyone? Could this be a istatmenu bug?

    here're some screenshots of istatmenu...

    Attached Files:

  2. philipma1957, Dec 11, 2011
    Last edited: Dec 11, 2011

    philipma1957 macrumors 603


    Apr 13, 2010
    Howell, New Jersey
    it is a software bug contact istats they may have a workaround
  3. spidey3 macrumors regular

    Jul 1, 2010
    Yeah, I have encountered this as well. Temp value read from the SMC needs to be subtracted from the base TjMax value defined for each CPU type -- but iStat menus doesn't do this.

    In practice, I have found that just reading the heatsink temps is good enough most of the time. If I need accurate values, I just subtract from TjMax (which you should be able to google to find for your processor type)...

  4. nambuccaheadsau macrumors 68000


    Oct 19, 2007
    Nambucca Heads Australia
    With a pair of X5355's CPUS are 36º and 39ª respectively with fan at 499rpm. And it is summer in the Southern Hemisphere.
  5. ryanide macrumors 6502

    Jul 23, 2002
    upgrade question

    I also have a Mac Pro 1,1 and I'm wondering what you upgraded the CPU to? Can you supply some details as far as where you bought it and what you ran into in the process of upgrading? How much did you have to spend and is it comparable to the new versions of the Mac Pro?

    Mine is loaded with 16GGB of RAM and I just replace the boot drive with an SSD which made a big improvement. But my new quad-core mini server (8GB RAM) beats the mac pro by about 25% -30% in handbrake encoding. I hate to just get rid of the mac pro, especially if a cpu upgrade will make a big improvement.

  6. macagain thread starter macrumors regular


    Jan 1, 2002

    I needed another Mac to run tests for my dev work. I looked around for a refurb'd Mac mini, but just couldn't find one for the right price.

    So I figured I'd make a holiday project out of it... I found a 3rd party refurb'd mac pro 1,1 2.0Ghz on ebay for $515. It was almost spotless. To top it off, it came with a 3Gb of ram, bluetooth, and wifi. What a deal.

    I picked up a pair of Xeon E5345's (Quad core 2.33Ghz) on ebay for $99, and 4Gb's of ram with apple heatsinks for $59.

    All the videos etc. on the web were a big help. I went about the cpu swap as prescribed. The most difficult part was removing the fan cage as everyone else has noted. The trick is to rock it back and forth, left and right. The sticking latch is a vertical catch at the base of the case, right where you can't get your fingers into!

    So, chips swapped, everything put back together. Plugged it in, and hit the switch. Nothing! No boing. My heart sank. I thought I got bad chips, so started the process in reverse, thinking I'd have to send the chips back. But once everything was in pieces, some wild hair made me decide to give it another try... So, I put everything together again, just like I did the first time, I thought.

    So, again, chips swapped, everything put back together (again). Plugged it in, and hit the switch. Boing!!! Success!

    Geekbench scores are around what everyone has reported... went from around 4200 to around 8200. Handbrake saw better improvements tho... on one movie, it went from 59mins down to 27 mins.

    I also tried adding some ram w/o the "apple approved" heatsinks (i.e. with the "Normal" heatsinks)... Not good... they were running hot and kept the fans running 800-1200 rpm constants (which is the diff between audible and inaudible). So out they came. May add more with the approved heatsinks later. Maybe new GPU...

    So, for around $675, I think I got me a pretty kick ass machine! I'd definitely do it again.

    Attached Files:

Share This Page