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RAM: Speed vs Quantity
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Join Date: Feb 2008
Location: Mile High
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Feb 3, 2011, 11:29 PM
Not the speed as in MHz, but as in dual channel vs triple channel.

On my Nehalem QC Mac Pro I usually run Adium, Transmission, OmniWeb, NetNewsWire, GyazMail, (optimized) Thunderbird, LaunchBar, WeatherDock, Sophos, BOINCMenubar 2, iCal Viewer, Luna Menu, SMARTReporter, Flux, Dropbox, LittleSnitch, DefaultFolder helper, ShoveBox, SlimBatteryMonitor, Evernote helper, and iStat Menu 2. BOINC runs all the time as a service, and sometimes I use Photoshop, Handbrake, FCE, etc… and I logout when I am not using the Mac.

Currently I have 2GB x 4 RAM which runs as dual channel. If I remove 1 stick the remaining 3 will run as triple channel, the question is which way will I get more benefit? Also I plan on upgrading sometime in the future to 4GB sticks, would 12GB at triple channel be better than 16GB at dual channel?

Thank you Intel for this unintuitive design, this would be so much easier if I had Sandy Bridge's quad channel.
Join Date: Jun 2000
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Feb 4, 2011, 01:10 AM
You've got so much running that I'd expect the extra RAM channel to help. But it looks like you need a lot of RAM too. I'd say to pull one stick and watch your production rate for a week. Also use Memory Monitor with slowest update speed to see if there's a lot of paging going on.
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Join Date: Oct 2005
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Feb 4, 2011, 01:47 PM
I absolutely disagree. Unless you're running workloads that are known to be memory bandwidth sensitive, you're always better off with more capacity.

The fault for the tradeoff is Apple, not Intel - the Intel chips support 3 modules on each of 3 channels, but Apple chose to cripple the Mac "Pro" with just 4 slots per socket. Proper workstations from Dell/HP/etc have 6 or 9 slots per socket.
Penguirl  (op)
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Feb 11, 2011, 01:00 AM
Since pulling the 4th stick of RAM I have watched my RAC steadily climb, which leads me to believe that BOINC, or at least some of the projects, is memory bandwidth intensive.

reader50 thanks for the Memory Monitor link. I found it hard to keep up with the page in/out but the help file led me to this cl gem: vm_stat * (* being the interval in seconds). This allows you to scroll back and see the page in/out numbers, as well as giving a running total every so often.

mduell At this time I am just looking to optimize my BOINC RAC, I will be installing three 4GB sticks just as soon as I can afford to. Usually I max out my Macs but it's going to be a good long while before I can afford three 8GB sticks at $2** apiece. Think I'll have to wait for them to come down a little
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