Number of cores 4 (max 4)
Number of threads 4 (max 4)
Name Intel Core 2 Quad Q6600
Specification Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz
Package Socket 775 LGA (platform ID = 4h)
Extended CPUID 6.F
Core Stepping G0
Technology 65 nm
Core Speed 1856.7 MHz (6.0 x 309.5 MHz)
Rated Bus speed 1237.8 MHz
Stock frequency 2400 MHz
It looks like you have 'Speedstep' or 'EIST' turned on in the BIOS.
Basically when this is enabled, the multiplier is reduced to x6 when the CPU is under no/light load. This is to save energy and produce less heat.
Change your FSB back to stock, then either perform a stress test on the CPU and see what the clock speed is at the same time, or turn off the EIST or Speedstep in the BIOS.