John20904
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Q: Older (1.1) Mac Pro runs SLOWER with RAM upgrade.

I have an older Mac Pro. I've been running it with 8 megs of RAM until just recently. RAM boards included original 4x512K chips that came with machine, plus 1Mb chips I had added, so I was using all 8 slots to get only 8MB of RAM. Bought 4x2mb to put in slots previously taken with the 512 chips, so new total would be 14Mb.

 

With new RAM installed (14MB total) the machine ran slower. One thing I noticed is that when the full 14mbs were installed, even though the systems saw them just fine, the additional memory was not being used, according to Activity Monitor - apps like Lightroom and Photoshop were absolutely crawling, but LOTS of free ram showing on the monitor.

 

All else being equal - plenty of HD space, etc- removing the additional ram restored its previous performance. Now, instead of both RAM boards, I'm just using one memory board with the newer 4x2 Mb modules, totaling 8 mb RAM, while the second board holding older chips worth 6MB sits on my desk. Performance is better but gosh darn it I'd really like to use, and benefit from, the additional 6mb of RAM!

 

What the heck?

MacPro, Mac OS X (10.4.8)

Posted on Nov 25, 2015 9:36 AM

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John20904

Q: Older (1.1) Mac Pro runs SLOWER with RAM upgrade.

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  • by John20904,

    John20904 John20904 Nov 26, 2015 10:06 AM in response to lllaass
    Level 1 (0 points)
    Nov 26, 2015 10:06 AM in response to lllaass

    I think I discovered the problem, and it has nothing to do with the RAM. The 2007 CPU is just too feeble for the 2015 apps I'm running. In Activity Monitor I can see that the CPU is maxed out by the processes I'm trying to do; I think having more RAM installed actually makes it worse, the additional RAM causes the CPU to work harder compared to having less RAM and therefore more VM/scratch disk hits. Having to use VM seems to ease the load on the CPU, although it should be slower to do so, the CPU doesn't show as much burden with less RAM; With more RAM, the CPU is getting maxed out, so the processes are actually slower.

     

    Happy Thanksgiving!

  • by lllaass,

    lllaass lllaass Nov 26, 2015 10:54 AM in response to John20904
    Level 10 (189,435 points)
    Desktops
    Nov 26, 2015 10:54 AM in response to John20904

    That does not seem right. While it is true that adding more memory may not increase speed if the running apps are CPU (or I/O bound), adding more memory should not slow apps to any noticeable degree.

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