Our Overclocking Experience
Gigabyte is one of the few manufacturers like ASUS and MSI that are supporting the overclockers to the full extent. Not only do you have the options to overclock your CPU and video card (that's right, video card) manually, but you can allow the system to overclock for you when the CPU usage is high.
Gigabyte's auto overclocking is called the C.I.A.2 or CPU Intelligent Acceleration 2. This feature (and all of the overclocking features) are located under the MB Intelligent Tweaker (M.I.T) menu of the Award BIOS - to unlock all of the overclocking features, once you enter BIOS, you need to press the CTRL+F1 keys to allow the hardcore overclocking and tweaking menus. These menus are hidden so OEM's can stop the less than informed user from playing around with the major CPU and memory settings.
The C.I.A.2 settings are Disabled, Cruise, Sports, Racing, Turbo and Full Thrust. Each setting has a limit on how far it will push the FSB above standard when the CPU usage is high. Disabled allows you to manually set the FSB if you want to do it yourself. Cruse allows for 5-7%, Sports 7-9%, Racing 9-11%, Turbo 15-17% and Full Thrust goes from 17-20%. While not only increasing the FSB, it also slightly raises the CPU voltage to accommodate the extra power needed to keep the CPU stable.
If you decide to do it yourself, you have the ability to change the FSB< PCI-E, DRAM clocks as well as the voltages for the DRAM, CPU and PCI-E.
CPU FSB adjustments can be made from 100MHz up to 600MHz in 1MHz increments, by far the biggest margin we have seen from any motherboard maker on the 955 chipsets, whether or not we get stability at these speeds is another thing though but the options are there for hardcore overclockers.
PCI-E can be set from 90MHz up to a maximum of 150MHz in 1MHz increments, though to keep things stable, best to keep the speed at 100MHz at all times which is the default for PCI-E.
Memory dividers allow you to set the memory to a base frequency based on the FSB of your board. No matter what CPU you use you have the following base frequencies, 400, 533, 667, 800MHz allowing you to overclock from this point with your memory is a great feature, as higher memory speeds in DDR-2 are coming out all the time it seems lately.
Now we move onto voltage options, and let me say, there is quite a good amount of juice you can pump into your parts. CPU voltage can be adjusted from 0.8375v up to a maximum of 1.6v in 0.025v increments, while this may seem low, remember, Prescott only runs at 1.38v at default, leaving you quite a bit to work with.
DRAM voltage is also quite plentiful with settings from +0.1v to +0.6v in 0.1v increments. This means you can set your memory from its default of 1.8v up to 2.4v, very handy for the OCZ memory that has an extended voltage rating of 2.2v.
PCI-E voltage is kind of redundant considering that most people keep the PCI-E bus at the 100MHz level. If you are the advantageous type who want to overclock everything, then this is for you, adjustments are from +0.1v to +0.35v in 0.05v increments. This gives a total from 1.5v up to 1.85v in the real world.
The last option in the voltage range is the FSB. This is for everyone overclocking. Despite the name it's the voltage supplied to the Northbridge chip, stabilising overclocks of the FSB and the memory bus. Options are from +0,1v up to +0.35v which gives the same voltage range as the PCI-E and the results - 1.5v to 1.85v.
With all these options we managed to get our test system of a Pentium D 840 with 1GB of OCZ PC2-5400EL memory up to a maximum FSB of 354MHz using a 1:1 memory divider and raising the CPU voltage to 1.55v, DRAM voltage to 2.2v, PCI-E at default voltage and FSB voltage to 1.6v.
Trying for higher settings with more voltages just led to unstable systems. We managed to keep this system stable for 3 days with contestant prime95, 3DMark loops and media encoding tasks to really push as much through the system as possible - in all a fantastic overclocking effort from Gigabyte. We have had claims of reaching 1066MHz memory speeds; however, we haven't been able to break this just yet. Once our test board returns to us we plan to investigate this to its full extent, as we do believe this is quite possible with higher rated memory from Corsair and Kingston.