I will explicitly point out some "gotchyas" that occasionally catch people who are adjusting the device profile.

1) BOINC originally used device profiles set on the web site. These are now called "General' preferences. It has recently added "Local" preferences, stored on the local computer. If at start up, the BOINC Manager writes in the Messages Tab that it is "Reading preferences override file", then you can stare at the web site preferences all day long without seeing where the problem is. Your computer will use the Local Preferences rather than the General Preferences. But BOINC does not show you what the current preferences are without prompting, since that was not part of the original design. You can read (or create) Local Preferences by running BOINC Manager in the Advanced View and selecting Advanced - Preferences. If you then select Clear in the Preferences popup, BOINC will clear the Local Preferences file and use the web site General Preferences.

2) Communications: BOINC originally sent and received all files without compression, which was horrible over dial-up. It listed the uncompressed file size being transferred. Compression has been added in stages. BOINC 5.10 now uses compressed files for both uploads and downloads, so anybody on dial-up will definitely want to use BOINC 5.10+. However, the messages still mention only the uncompressed file size ( the original design), which confuses people who expect to be told both compressed and uncompressed file sizes when using compression.

3) The Basic Options has the following line by default:
"Use no more than: 60.0% of processor time"

This one is surprisingly tricky. If you select the "Maximum Output" setting, it automatically changes to 100%, which is what I use. But many laptops do not have as much cooling capacity as a desktop computer, so the default WCG Custom Profile chooses to run the CPU only 60% of the time. The intent of this choice is to help new members with laptops that have cooling problems. BOINC is designed to run on many operating systems, so this option works in whole seconds (10 seconds maximum). That is, 90% will run the CPU for 9 seconds and shut it off for 1 second. Not much cooling. 80% will run for 4 seconds and stop for 1 second. A little more cooling. 70% will run for 7 seconds and stop for 3. 60% will run for 3 seconds and stop for 2. 50 % will run for 1 second and stop for 1 second, which I consider the coolest choice. If you have to run even slower, then something is probably wrong or misunderstood.

Since CPUs are designed to run at 100%, anything less than 100% should only be chosen if there is a special problem to deal with. Normally, only laptops will have a cooling problem.

There is a third-party method for use on Windows computers that works much more smoothly. If you use ThreadMaster and ThreadMaster GUI (explained by Sekerob in Start Here at http://www.worldcommunitygrid.org/forums/wcg/viewthread?thread=16084 ) then this BOINC option should be set at 100%. ThreadMaster is really much better and more powerful than the BOINC method, but it is operating-system dependent. I do not know of an equivalent for Linux or Mac OS X.

Be aware that BOINC runs projects at lowest priority. The recent AMD "Barcelona" quad-cores may automatically slow down any cores that are only running lowest-priority threads in order to conserve power. It all depends on the OS settings. Ubuntu Linux has surprised several of our members who discovered that this power-saving option was selected by default. Intel's coming "Nehalem" chips are rumored to also have this power-saving circuitry design.