In the past it wasn't so difficult to overclock an Intel CPU even if the mainboard didn't support FSB overclocking. Thanks to the different straps, preset FSB in CPU registry, we could pinmod the CPU to run at 266, 333 or 400MHz BCLK. With the new Nehalem platform, however, we can only overclock by increasing the BCLK frequency; in contrary to the previous LGA775 platform, this reference clock doesn't come in different straps, making it more difficult to overclock without mainboard bios tools.
Pain_666, a Russian overclocker, has found a workaround for this problem. Instead of modifying the CPU itself, we modify the default setting of the PLL. Doing so, we can increase the BCLK from 133MHz to 166 and even 200MHz!