I think this is a mobo issue. My Optiplex 745 is OEM. CPU-Z indicates that my Intel Core 2 Duo firstname.lastname@example.org is only runing at Core Speed 1595.9 MHz. The Multiplier is x6.0. The Bus Speed is 266.0MHz. The rated FSB is 1066. But good luck trying to get into the BIOS to change the multiplier from x6.0 to x8.0 which would bring the actual core speed to the rated 2.13GHz.
Where or how the heck do I tweak this Dell Mobo to run at the correct x8.0 multiplier?
This PC has been a dog since day #1. Adding 4 X 1 Gb Corsair DDR-2 memory for a total of < 4 Mb has helped. But an Intel Core 2 Duo 6400 should run at 6400 MHz, not 1.6.
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The Intel Core 2 Duo has SpeedStepping. The core speed is at on x6 when idle or little load, but "steps" up to x8 when the CPU needs the juice. So running at only 1.6 MHz is exactly what it's suppose to do until the need for more speed is needed, then it shifts into x8 multiplier attaining the spec'd 2.13 MHz.