Intel Core i7-3820 Sandy Bridge-E CPU Review

Author: MAC
Date: February 22, 2012
Product Name: i7-3820
Part Number: BX80619i73820
Warranty: 3 Years
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Overclocking Results

Overclocking on Sandy Bridge-E is very similar to mainstream Sandy Bridge, except for the fact that itís generally better in every way. There is more bus speed headroom, the memory overclocking is significantly improved, and there is the great new gear ratio feature that acts as an additional master multiplier for both the processor and memory. First, the Gear Ratio (or Reference Gear Ratio / Host Clock Multiplier) comes in three flavours: 1.00, 1.25X, and 1.66X. How you use it is simple. Letís say you are using a 40X CPU multiplier, 100MHz bus speed, and your memory is running at DDR3-1600. If you switch the Gear Ratio from 1.00X to 1.25X, your processor overclock will jump from 4.0GHz to 5.0GHz, your memory speed will increase from DDR3-1600 to DDR3-2000, and your bus speed will stay at 100MHz. So you can achieve a huge overclock without having changed the CPU multiplier, memory multiplier, or bus speed. As a result, even the i7-3820, which is Ďpartially lockedí and has 43X CPU multiplier cap, should be theoretically capable of hitting some lofty clock speeds. Our only slight disappointment is that the memory dividers are still in large 266MHz increments, but we will have to wait for Ivy Bridge before this situation is changed.

Click on image to enlarge

Although we always want more, given how easy it was to achieve we can't help but be satisfied with this overclock. 4.75GHz at 1.45V is within the 4.6-4.8GHz range that most Sandy Bridge LGA1155 chips are capable of, so we aren't really reaching new heights, but hitting such speeds on the LGA1155 platform is generally a more involved process. With Sandy Bridge-E you no longer have to toil away trying to determine your maximum multiplier and bus speed, the new gear ratios take care of much of the work.
You can fine tune your overclock by increasing the bus speed, but you are going to run into difficulties in the 105-107MHz range. In our case, it was as simple as selecting a 38X cpu multiplier, 1.25X gear ratio, setting the vCore to 1.45V and slightly bumping up VTT and IMC/VCCSA voltages.

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