Not sure why you'd set the multiplier to 20 for a i7 950? - its default is 23.
Anyway, a good place to start is also probably a forum for Gigabyte motherboards - I use an EVGA motherboard and EVGA have a fantastic overclocking section on their forum which gives very in-depth details about all the settings. My 920 is overclocked to 3.9mhz for my daily overclock with practically no extra vcore and just using a higher BCLK and a few other tweaks. I can easily get 4.2 but this requires a lot more tweaking and higher vcore with subsequent higher CPU and core temperatures.
Also check the default voltage of the RAM, my Corsair ram should be set to 1.65v but the motherboard by default sets this to 1.5v and therefore needs to be set to the correct setting of 1.65v in order to run it at its rated 1600mhz
Not sure why you'd set the multiplier to 20 for a i7 950? - its default is 23.
Anyway, a good place to start is also probably a forum for Gigabyte motherboards - I use an EVGA motherboard and EVGA have a fantastic overclocking section on their forum which gives very in-depth details about all the settings. My 920 is overclocked to 3.9mhz for my daily overclock with practically no extra vcore and just using a higher BCLK and a few other tweaks. I can easily get 4.2 but this requires a lot more tweaking and higher vcore with subsequent higher CPU and core temperatures.
Also check the default voltage of the RAM, my Corsair ram should be set to 1.65v but the motherboard by default sets this to 1.5v and therefore needs to be set to the correct setting of 1.65v in order to run it at its rated 1600mhz