That has always been the case, control for 3 of 4 fans. And best utilty to monitor temp appears to be iStatPro or Hardware Monitor.
Other than the MacPro2,1 firmware EFI upgrade the next step might be surprise to see just if and how much dust can get pulled into and empacted in the PSU. There are guides and video on youtube how to disassemble, some that were part of the "how to upgrade cpu".
DVWarehouse and I think I have another link to places that sell that PSU. The MacPro 5160 and 5365 had larger PSU I am 90% sure too.
I have an upgraded (2 x X5355 8 core) Mac Pro 1.1 running 10.7.4. I routinely use SMCFanControl (the latest version) to ramp up the fans when I am running long, CPU-intensive jobs. However, SMCFanControl only changes three of the four fans - the PSU fan remains stuck on 600rpm, regardless of the settings...
That's a good question. It's been a while since I've run my 1,1 Mac Pro, but I remember that smcFanControl could change everything but the PS fan (which is at the front of the PS brick, right behind the DVD drives - I just took the cover off and doublechecked). On my current Mac Pro, which has the same DVD/PSU layout, smcFanControl can control all the fans.
Agreed. My 2006 Mac Pro's PSU had never been dusted, so yesterday I removed it and blew it through with a can of compressed air. It was very, very dusty. Previously the "resting" sensor 2 temperature inside the PSU was 65C. Now it's 42C.
Also, do you know which variant of the X5355 you fitted? Not all X5355s are identical. The "SLAEG" variant will probably run cooler in an upgraded Mac Pro because when idle it can go into a low-power state, consuming about half the power.
I blew my PSU out prior to the upgrade (it was quite dusty) and my current PSU (location 2) resting temperature is mid 40s with the fans on default settings. I usually blow my machine out once a year, although I do keep an eye on my graphics card, as it collects a lot more dust than anything else.
Unfortunately, I do not remember what variant of X5355s I installed. For what it is worth, with the fans on default and the machine idling in a ca 20C room, the CPUs sit at around 45C, so I am guessing they are probably not the low power variants.
A good tip that. I took out my second drive and the PSU temperature dropped likewise. The vertical gate on the superdrive I removed tends to stick open, so I just left it open. If yours doesn't stick, then you could chock it with a match stick or similar. This lowers the temperature of the PSU another 5degC. From a peak of 94C (eek!) with two DVD drives present, my PSU was sitting at 65C today after running with all 8 cores flat out all day and overclocked from 2.66 to 3Ghz.
Today I moved the DVD drive to the lower slot and moved the IDE cable flat behind the drive out of the airflow path. Its now down to 48c at idle and 64c after 15 minutes at maximum load.
Amazing what the little details can return.
Still, it would be nice to bump up the fan a hundred rpm, but I can't find anything on how to do it other than adding a fan in front of it powered by the DVD molex plug.