SUMMARY: Possible frequency mods to Intel Multi-Core LGA775 CPUs.

NOTE: The following data is from Intel Data Sheets and is summarized for information purposes only. There is no guarantee that any modification to a CPU will be successful in changing the CPU's frequency. Overclockers.com will not be held responsible for any direct or consequential damages should these modifications be implemented.

I received a lot of email on FSB modding LGA775 CPUs and thought a guide on this would be valuable - there are numerous threads in forums on this mod, so there is nothing new here but it summarizes what's possible.

Intel's LGA775 series CPUs are some of the most overclockable CPUs we have seen since the early Celeron days. Many users are achieving substantial overclocks on these CPUs by physically connecting pads on the CPU to change its frequency. The following table shows what combinations are used by Intel to set the CPU's frequency signals to the motherboard. The "H" and "L" refer to voltages on the CPU pads, with "H" a positive value and "L" negative:

Note that these series use the same BSEL combinations to achieve frequencies - collapsing all the combinations to one table gives the following:

All the LGA775 Multi-Core series have their BSEL pads in the same location:

The basic methodology for FSB changes involves the following:

• Connecting an "H" BSEL pad to a VSS pad changes a High value to Low
• Connecting an "L" BSEL pad to a VCC pad changes a Low value to High

To connect the pads you can use a conductive paint such as this:

It is essential that you do not paint the wrong pads and critical that you do not get any paint on other pads. I have used a mask to keep the paint from flowing onto other pads:

The basic strategy to FSB modding is to take a low frequency CPU and mod it to a higher frequency - if you have a 333 or 400 MHz CPU operating at a high speed already, there is not a lot of headroom for a jump to a higher speed with pad mods.

Based on the above data, there following mods are possible, although whether any of these will be successful is an open question:

• Connecting an "H" BSEL pad to a VSS pad changes a High value to Low
• Connecting an "L" BSEL pad to a VCC pad changes a Low value to High

The following mods are possible - these are top views of the left bottom of the CPU, where EF is the indexing notch (actual CPU pics on page 2):

The following strapping will change a 200 MHz CPU to a 333 MHz CPU:

In some instances just covering BSEL2 with a small piece of tape will change BSEL2 to high - this worked with my E2160 on a Dell Vostro 200. Whether this will work with other CPU/mobo combinatons is open to experimentation. It might be possible to change a 200 MHz CPU to run at 400 MHz, but most likely this will not work as the jump from 200 to 400 MHz is probably too far.

One other possible mod is to change a 266 MHz CPU to 400 MHz:

I have not seen this done so I can't attest to its viability - however, the E6300 is a good candidate for this mod - 2.8 GHz is probably attainable without extreme cooling, but whether the motherboard supports 400 MHz is a determining factor.