Intel LGA775 Pad Modding

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Possible frequency mods to Intel Multi-Core LGA775 CPUs – Joe

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:

Intel Multi-Core LGA775 CPU Series Frequency Tables

CPU Series

BSEL2

BSEL1

BSEL0

FSB Frequency

Intel ® Core ™2 Extreme Processor
QX9000 Series and Intel ® Core ™2
Quad Processor Q9000 Series

H

H

L

400

H

L

L

333

Intel ® Core ™2 Extreme Processor
X6800 and Intel ® Core ™2 Duo
Desktop Processor E6000 and
E4000 Series

H

L

L

333

L

L

L

266

L

H

L

200

Intel ® Pentium ® Dual-Core Desktop
Processor E2000 Series

L

H

L

200

Intel ® Celeron ® Dual-Core
Processor E1000 Series

L

H

L

200

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

Intel Multi-Core LGA775 CPU Series Frequency Tables

CPU Frequency

BSEL2

BSEL1

BSEL0

400

H

H

L

333

H

L

L

266

L

L

L

200

L

H

L

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

Pic

CPU view from the top

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

VCC are the power pins for the processor and carry a positive charge and VSS are the ground pins for the processor and carry a negative charge.

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

Permatex Conductive Paint

Pic

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:

Pic

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.

Summary of Theoretical Combinations

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

Intel Multi-Core LGA775 CPU Series Frequency Tables

CPU Frequency

BSEL2

BSEL1

BSEL0

400

H

H

L

333

H

L

L

266

L

L

L

200

L

H

L

  • 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:

Pic
Pic
Pic

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

Pic

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:

Pic

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.

The following pictures show the mods on an actual CPU; first, the CPU’s back where the BSEL pad area is located:

Pic

Here the lower right hand side of the CPU with the pads identified:

Pic

And the mods in detail:

Pic
Pic
Pic
Pic

Note: An alternative that may work for 200 to 333 MHz is to cover BSEL2 with tape or paint over it to insulate it.

Pic

CONCLUSIONS

Pad mods on the LGA775 Multi-Core CPUs can yield some very nice overclocks – I’d appreciate comments on successful pad mod overclocks to 400 MHz.

This data may also apply to other LGA775 CPUs – check Intel’s Data Sheets for details on FSB pads.


Useful Links

Intel CPU Terms – A glossary of CPU terms
Intel Processor Spec Finder – Find specs and datasheets on Intel CPUs

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Discussion
  1. ah good ole pad modding.... love doing it to 775 cpus... its SO EASY!
    done multiple vcore pad mods to undervolt 775 cpus in mobos that dont support undervolting :)
    What's the difference between the LGA 775 and LGA 771?
    I have a Harpertown 1333 X5450 I'd like to bump from 333 to 400mhz.
    It's an Intel Xeon CPU in a LGA775 socket. How does the BSEL work in this combo?
    Thanks
    I have retro mobo Asrock 775i65G R3.0 and I have Pentium dual core E6500K. The mobo does not allow to change vcore, and FSB to DRAM if you have 1066 fsb processor. I need to mod vcore E6500K to 1.4v - 1.5v I think to run about 4 GHz and I need to change processor FSB from 1066 to 800 to unlock FSB to DRAM to 1:1. Help me please, how to do it?