After monitoring this thread, a couple of us did some experimenting. The results are as follows:

1). Unless you change your other settings, only the cpu rating changes.
2). If you run any other applications that demand a fair amount of cpu power, this will be reflected in a lowering of your cpu score. (ie, Word will not.)
3). This application competition for cpu resources will affect the cpu score at any time it is run, and for the length of time it is run, during the processing of a particular WU. There must be a continuous monitioring process going on.
4). Cpu temp will effect the score, particularly if there is an integrated throttle back mechanism built into the mobo.
5). If temp is held constant, the only variability that we can detect is caused by other applications drawing cpu resources away from Rosetta.
6). It is so reliable a relationship, that we can use the processor score to figure out what was running in the background, and for how long.

For example, I have an AMD 1900+ 1.66GHz that returns 158 max for the processor score. If I run a bunch of other apps simultaneously, I can lower the score by 10 points, max.

The conclusion of our little experiment is: If temp is constant, then ...

1). something else must be running in the background that is drawing resources away from the processor.
2). or, the processor itself is not functioning properly.

No matter what, we will be curious to find out what you determine was the cause of the problem. Good luck.

hello fj,
You will have to give us more information identifying your Athlon 64. However, it is not a secret that some of the lower Pentium-equivalent ratings (PR) are overstated. AMD was conservative for some years, but recently overstated some PR figures to avoid dropping too much when switching to new cores. If my memory is correct, 3100 and up is still accurate but the lower speeds on some fairly new chips overstate their speed.
mycrofth

I run an AMD64 3000+ at home (Newcastle 2.0 GHz). My CPU rating is almost always near 199 (give or take). On my 1.6GHz Pentium M laptop, my score is normally in the 150 range. However, this morning it's 108 because it happened to do the benchmark when my AV scan was running, thus lowering it.

The CPU rating is calculated by a very quick benchmark running at low priority, just before a new workunit is started. The reason it's run at low priority is to benchmark your system under the same conditions the task runs. e.g. if you are running Rosetta on a powerful server, but the server is busy 50% of the time serving data, then your CPU score will be roughly half what the same CPU would rate under idle conditions. The benchmark is VERY quick (lasts only a few seconds), so the chances of it running at a time when your computer is busy when it's normally not, are small. However, over time the ratings balance out and provide a more or less accurate rating for your CPU based on usage over time.

Since the benchmark is run only once at the beginning of each workunit, the CPU rating remains the same throughout a single workunit. Running other apps while processing a workunit do not change the CPU rating.

Most home computers shouldn't vary much from "nominal" scores for their CPU. However, games, AV scans, malware scans, Media player graphics, ripping MP3s, browsing sites with lots of flash or busy Java applets, image processing on photos, etc. all take significant CPU time (to a varying degree), so if you download a new workunit when doing any of these activities, your CPU rating will be lowered to some extent.

There are a number of variations. If you download a free copy of SiSoft Sandra ( http://www.sisoftware.net/?location=update ), then you can ask it for CPU Information. Among other things, it will give you an estimated PR (performance rating). And it has the standard benchmarks.

My athlon64 3000+ continually scores 201. regardless of any circumstances.

My 3.4 ghz P4 has scored as low as 73 and as high as 180 and almost every number in between.

cheers!!!