smcFanControl sits in the menu-bar and allows me to pull down and select from a fairly large number of presets. It also displays current CPU temperature.
MenuMeters also occupies space in the menu-bar and (as I have it configured) shows:
- CPU Usage history on all 8 cores individually,
- Current drive activity,
- Current number of memory pages,
- Network activity history + current TX / RX
- Memory usage history,
I'm always aware of how much CPU usage is taking place and for 1 minute or so of history. If it gets heavy I also glance at the CPU temp. If that is crawling up I select a faster fan-speed from the drop-down menu. When I'm finished doing whatever it is I lower it back down.
Apple's SMC in the 2006 machine is all but broken! It ignores all sensors but the CPU. When the CPU temp hits 75 or so then it bumps up the fan speed just slightly like +50 RPM. If it still continues to rise it will increase more but it never seems to be enough and it can hit 80c or the max Intel rating of 85c very quickly. This alone wouldn't be a huge deal but for the fact that in such conditions my drives (the ones I used to have) would also start increasing temperatures till they were exceeding the manufacturers Max Operating temp of 50c. Also this condition was often accompanied by crazy RAM temperatures.
My new drives are rated at 65c so there's a LOT less to be concerned about but now I'm in the habit anyway. By doing all this manually (with the menu selection) I can be cloning drives, rendering with CPUs at 790%, and writing messages here
and the CPU never goes above 45c, the drives never hit 35c and the RAM stays reasonable. These temps leave the 2006 Mac Pro responsive and stable even under that kind of abuse. I dunno if it's the clock-clipping or just the heat but if I don't do this then when such temperatures are reached the machine lags, things crash more easily, and of course I know it's killing some of it's life-span.
Apple has taken 2 shots at trying to "fix" the SMC and fan behavior and have failed - so I have to do it by hand. I don't mind tho - it's even kinda fun! I only spend maybe 10 or 15 seconds in a busy day doing this so it's not all that bad either.