Fan Control

Fan control is built-into OS X and the computer's firmware. Not only is there no need for fan control software it will not improve the performance of your computer, it could mask a real hardware problem, and it may void your warranty.

I own six different Mac models none of which use any third-party fan control software and all run perfectly normal. Leave well enough alone and assume that Apple's engineers know a little more about cooling technology than you do.

It isn't going to harm, void, or interfere, and I consider it ESSENTIAL!

All you are doing is creating a couple profiles for different minimum fan speeds.

The Mac Pro is definitely faulty in not kicking the fans in when needed and early enough - harder to dispell heat than it is to prevent in the first place.

Just make sure it is SmcFanControl 2.x or later. It only manages 3 of 4 fans.

Helps keep FBDIMMs cooled and just improves airflow.

I disagree. In the nearly four years I've had my MP I've never had a heat problem, and I've never needed fan control for it or my laptops which include the original MBP. I've seen no real benefit from using fan control software over that provided with the SMC. I would hardly consider it essential.

200F does seem high to me. My Xeon 8-core Mac Pro, which has the original pair of 1GB RAM modules with the big Apple heat sinks, and then a pair of Kingston valueRAM 4GB modules with plain ol' flat metal heatsinks, normally idles in the 50-55C range (122-131F) and will go up into the mid-80'sC (~185F) on prolonged, very heavy use.

Using SMCFan control on a Mac Pro is harmless. You can reset the controls to the defaults and quit the app at any time. Unless you specifically set up the preferences to do so, it will not load again automatically on a reboot either. It does nothing permanently to your system at all. It will show you speeds for 4 fans, but you cannot control the power supply fan with it (CPU, IO and ExHaust fans can be controlled). I used it for awhile when I first got my Mac Pro just because I was not used to the hot FBDIMMs, but since found I really do not need to use it as my system is stable and fine (and this is my work machine, so is on 24/7 and on a daily basis gets heavy CPU and RAM use).

The last similar problem I dealt with on the AD resulted in the discovery of a bad DIMM. It was discovered by removing pairs until the temps returned to normal. You might consider that.

CPU = 500
Exhaust = 600
HD/Expansion = 500
Power Supply = 680

These are the nominal speeds.

Right now the hottest temperature being measured reads 75ºC for Memory Module B4 (Riser B is the bottom Riser.) My MP is normally running 16/7.

It does sound to me that in this case you are treating the symptoms, and not the cause.

I would urgently be seeking to know why the temperatures are so high, rather than simply increasing fan speeds.

I agree there can be a case for intervening and getting the fans going sooner, but this sounds more like an under stressed computer, with faulty RAM, rather than one which is under heavy load and sweating.

Try swapping out pairs of RAM, particularly the OWC upgrade RAM, if that fixes the temps call OWC, the RAM should have lifetime warranty. Or buy a fresh (larger?) pair from another source and install just that to eliminate?

I've been using smcfancontrol for almost 4 years, and there have been no problems whatsoever. Using it basically comes down to environment and just plain preference. Default speeds might work great throughout say a seasonally cool area, although throw a mac pro with default fan speeds in the desert, and i would feel uncomfortable running it like that.

In the PC world, cooling vs. silence is a regular thing. Some prefer one to the other; being able to choose is what makes customizing so much better.

Btw...I also agree with Epochmaker, deal with the faulty ram first. I just wanted to throw my 2cents in on fan control, lol.

Interestingly on ambient temperatures, I have just turned my heating on because the room temperature in my flat has been at 10ºC for 24 Hours, I raised it to 12.5 ºC room temperature.

The Mac mini I am currently using went a very rough average 9ºC hotter across all the sensors, for a 2.5ºC raise in ambient. It's still running well within limits, but it just shows how the room temp can affect the computer temps.

200F for the power supply is too high, IMO. What program are you using to measure the temperature? Is it current? Have you looked inside the case and confirmed that the fans are running as indicated (I know you cannot measure their rotational speed by eye, but you will have an idea of whether they are working at all, or if they are, are they clearly slower then they should be), that nothing (dirt, dust etc) is obstructing air flow?

My power supply shows two sensors using iStat Menus (vers. 2.0) and they are currently at 62C and 57C (so less then 144F) and they rarely get above 70C - the power supply temps are by far the least variable on my machine. My four memory modules (A1, A2, B1, B2) are sitting between 37C and 43C, and CPU's are sitting around 26C. iStat says the ambient temp is 22C (71.6F). Top shows my load average right now as 2.19 and I currently have 1.37GB of of 10GB (total installed) free (0 page outs).

My Fans are running at their defaults:
CPU_MEM = 500rpm
IO = 800rpm
Exhaust = 600rpm
PS = 600rpm

This is all for a 8-core 2.8Ghz early-2008 Xeon machine (10GB RAM, single 1TB hard drive). It is running OS X 10.5.8 (in my sig., it is my personal MBP that is running 10.6)

SMC Fan Control does nothing permanent to your system. You can launch it, use it, close it, repeat as you want, it makes no permanent system changes at all. It cannot void you warranty since all it is doing is altering fan speeds within the limits defined by the system. It will not allow you to set fan speeds below the Apple determined minimums, nor to exceed the Apple determined maximums.