This program changes PLL registers over i2c/SMbus, and FSB clock speed changes too. If your PLL is not supported you can do following: 1. Download datasheet, read it, write support by yourself. Test it. Send code and results to me. That is the easy way. :) 2. Send email to me with name of your PLL and when possible with URL pointing to datasheet for it. Wait some time. Download new version with support for your PLL. Test it. Send results to me. That is the hard way. :) 3. Go to Bobrooysk and drink poison. That was the only option when no datasheet was to find. But now there is possible solution (requires windows). Under windows change FSB frequency with manufacturer tool (AMD Overdrive or what ever) and dump i2c registers for 10 different frequencies in desired range. Send this data to me. Then I can try to reverse engineer the magic formula for your PLL. Worst case scenario would be table for fixed frequencies, most overclockers don't require that much of them. To check PLL i2c/SMbus availability run: i2cdetect -l i2cdetect X i2cdump X 0x69 s (read manual, block read/write is not always possible) X is the number of your bus. And yes, this program can damage your hardware. Also make sure not to use the TSC time source when using this program as this time source is included in the CPU and run at wrong speed after changing FSB. You can accomplish this by adding a boot parameter from your boot manager "clocksource=hpet" or from command line with: "echo hpet > /sys/devices/system/clocksource/clocksource0/current_clocksource" If hpet is not available use acpi_pm. Check /sys/devices/system/clocksource/clocksource0/available_clocksource for available clocksources. If you can't see i2c bus of your MoBo check boot messages for ACPI resource conflicts. Boot parameter "acpi_enforce_resources=lax" can help in this case. Parameter "clocksource=acpi_pm" can help unhide PLLs 0x69 smbus address.