Francois,
Let's make sure that we are comparing apples with apples, not oranges. By default, the Agent displays an 'Overall' Performance Rating. If you click on 'Processor', it switches to show the 'Processor' Performance Rating. My old AMD Athlon XP 2600+ running at 1.92 Ghz is rated 192. [Just coincidence, I feel sure]
The second thing to realize is that the processor rating is given by a small test that is run during installation and whenever a result is returned. So if a foreground process is running, it reduces the processor rating. The initial test seems to run during the installation process. It is always lower than later ratings run when no other process is running. Of course, there was one member who happened to check his Agent after running a game and discovered that his Processor Rating had dropped to 1! [Big Grin]
Over time, it should average out to give a true picture of how much CPU power you are applying to the World Community Grid projects. Of course, then there is the question of computing points awarded for various features. This can lead to qute a debate.

Lawrence

tell me about it, my Opterons 244@246 are rated just 170 :(

if you have background apps. running they will dominate cpu time as it runs on low priority

I'm going to look at your ratings. Might help me understanding why my ratings are lower than I'd expect most of the time. The processor ratings I got so far for my notebook (whose air cooling system is not extremely effective) using a P4 2.6 GHz range from 22 (three below 30 !) to above 170 (at least ten of them), with most ratings around 90 and 110, some around 50.

Nevertheless, can someone give us clues about how processor ratings are computed (are WUs benchmarked somewhere, etc.) ? The wierd thing is that they are rather often unrelated with computation conditions: some of the highest ratings corespond to a WU computed for a part when I was using the computer, unlike the lowest rating. There doesn't seem to be a strong relationship either with outer temperature (rathings are not necessarily higher when the PC is computing in a cooler place).

I know temperature slowdown is probably the main factor: I said in my previous post that the cooling system is not extremely efficient, and the sound emitted by the computer changes when the processor slows down (which is confirmed by the first tab of the System part of the Configuration Panel: it displays 1.30 GHz when the processor slows down, 2.60 GHz otherwise).
I have no screensaver (I disabled the WCG one), and I often monitor my processes, which reveals nothing wierd. Additionnally, it's been a while since I disabled a number of Windows services I don't need, which lowers the number of processes and threads (most of them did never eat up a single second of CPU time, since they were unused).

But the thing is, ratings can be unrelated to temperature slowdowns. Over as I saw extremely low ratings (20-30) correspond to a WU computed at a lower outer temperature (just another colder room of the house); on the contrary, I saw the highest ratings (170) being given with a WU computed while I was working with the PC, in a warmer room !
I noticed this over a set of 61 WUs (three returned today don't appear in the stats, and I think I'll return a fourth one, currently 4h10 @ 66%).