johnnym wrote:I'm afraid both System Profiler and Open Firmware will just show the frequency that's configured but not the frequency it was meant for. Maybe I'll try some other settings and test at what maximum speed the module can run and then conclude for which speed it was meant. Or maybe I remove the heatsink and check if the speed is readable on the dies. At least for PowerPC 7450s it looks like their meant speed is readable on the die.
I now checked the CPU dies and they seem to be meant for 1600 MHz:
According to PowerLogix (1, 2) this could be a speedy module, because they seem to have overclocked parts by 300 MHz or so.
I currently test the module with 1933 1866 MHz (according to this configuration table which could be wrong at the 1933 MHz line, as all previous steps were 66 MHz steps, so the next step after 1800 MHz would be 1866 MHz, which would be close to the value the system profiler reports) using openssl speed -elapsed in Mac OS X 10.5.8.The system profiler shows it with 1.87 GHz, but I'm unsure if this is correct, because when configured to 1800 MHz it showed 466 MHz instead.
Next stop: 2 GHz! Let's see...
...sadly doesn't work with the stock heatsink and fan
. Mac OS X 10.5.8 doesn't finish booting. So back to 1866 MHz. But compared to the 1333 MHz I used in the past - fair enough! 
EDIT:
Looks like I finally found the manufacturer info about my module. It's rated for 1800 MHz by PowerLogix, so maybe I should go back to the 1800 MHz I tested earlier, although the system profiler than shows a wrong speed.
...
).
