I have a 466MHz Power Mac (Digital Audio), I just noticed that System Profiler is reporting one of the sticks of RAM as PC100. It's a clearly labeled PC133 stick purchased from Crucial. I've tried swapping slots and it's still the same result. Is there anyway to determine what speed the FSB is actually running at so I know if this stick is under clocking and killing my bus speed?

the actual ram is 133 compatible.. the system takes 100mhz chips so it downclocks the ram to suit the comp.

In System Profiler, click on "Hardware". You will see "Bus Speed" listed in the Hardware Overview.

everymac.com lists the 466MHz Powermac as having a 133MHz bus. Makes sense given that the processor clock is usually a multiple of half the bus speed (ie 66 in this case). I would check System Profiler first, then run the Hardware Test CD.

You can also have a look at apple-history.com. Very good for this type of info...

Sorry guys I should have been clearer to begin with, I know the system supports a 133Mhz bus and will step down to 100MHz if if a PC100 stick is installed.

The problems is System Profiler is reporting a 133Mhz bus and that a PC100 stick is installed at the same time, one of them has got to be incorrect I'm just trying to determine which it is for certain. The RAM is labeled PC133 so I'm guessing that's the incorrect one, I just don't understand why the system isn't reducing the bus if it thinks PC100 RAM is installed.

I'm hopefully looking for a utility that will accurately report the bus speed so I can be certain, in this case I can't trust System Profiler either way.

If there is a hardware test CD for that machine I would run that before doing anything else. You could also try the usual panaceas - PRAM zap, repair permissions. If it isn't reported as PC133 after all that, send it back.

Stick the stick of RAM in another machine and see if you get the same result?

I'm 99% sure Macs don't have the capability to downclock their bus or memory speeds if running a 'slow' stick of RAM, ie. 100FSB when it should be 133FSB.

I'd bet Apple System Profiler is reporting the SPD setting of the RAM - which is a small chip on the RAM stick that reports it's CAS speed and type. I've come across many brand name sticks that are rated at PC100, but run at PC133 with no problems whatsoever.

If you're still unsure, run Xbench on your machine and compare the memory throughput speeds with an equivalent model posted on the Xbench database/website. If it's close to 33% slower memory bandwith, I'm wrong and it does downclock the bus speed.

JB