Hardware Reference
In-Depth Information
Overclocking Sand Bridge Processors
The Sandy Bridge Core i-series processors from Intel have made drastic changes in how
overclocking works. The clock generator is incorporated into the 6-series chipsets that sup-
port Sandy Bridge processors, so that you can no longer independently adjust the speeds of
buses such as PCI Express or DMI. The BCLK frequency is also locked at 100MHz (it was
133MHz with adjustments up or down in the Nehalem Core i-series processors).
IfyouwanttohavemaximumoverclockpotentialforaCorei-seriesSandyBridgeprocessor,
look for model numbers ending in K (for example, Core i7-2600K) and choose a mother-
board with a chipset designed for overclocking, such as the P67 or Z68.
Core i7 and i5 Sandy Bridge processors without the K suffix allow limited overclocking
(“limitedunlocking”)uptofourspeedranges(bins)abovethenormalturbofrequency(max-
imum clock speed). For example, a processor with a turbo frequency of 3.7GHz could be
overclocked to 4.1GHz with one core running, 4.0GHz with two cores running, and so on.
Again, you need an overclock-friendly chipset such as the P67 or Z68 to make this happen.
Core i3 Sandy Bridge chips don't include Turbo Boost and thus don't support overclocking.
Consequently, if you want to overclock Sandy Bridge processors, your choice of processor
and chipset is more important than ever before.
CPU Voltage Settings
Another trick overclockers use is playing with the voltage settings for the CPU. All mod-
ern CPU sockets and slots have automatic voltage detection. With this detection, the sys-
tem determines and sets the correct voltage by reading certain pins on the processor.
Some motherboards do not allow manual changes to these settings. Other motherboards
allow you to tweak the voltage settings up or down by fractions of a volt. Some experi-
mentershavefoundthatbyeitherincreasingordecreasingvoltageslightlyfromthestand-
ard, a higher speed of overclock can be achieved with the system remaining stable. Some
motherboards allow adjusting the voltage settings for the FSB, chipset, and memory com-
ponents, allowing for even more control in overclocking situations.
Myrecommendation is to be careful when playing with voltages because youcan damage
the processor or other components in this manner. Even without changing voltage, over-
clocking with an adjustable bus speed motherboard is easy and fairly rewarding. I do re-
commend you make sure you are using a high-quality board, good memory, and espe-
cially a good system chassis with additional cooling fans and a heavy-duty power supply.
See
Chapter18
formoreinformationonupgradingpowersuppliesandchassis.Especially
whenyouareoverclocking,itisessentialthatthesystemcomponentsandtheCPUremain
properly cooled. Going a little bit overboard on the processor heatsink and adding extra
cooling fans to the case never hurts and in many cases helps a great deal when hotrodding
a system in this manner.
