Intel Second Generation Core i7 3820 Reviewccokeman - March 15, 2012
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Introduced back in November of 2011, Intel's Sandy Bridge Extreme processors came as a long-awaited update to the company’s high-end enthusiast line. Socket 1366 and the X58 chipset have served well, but at this point in time, even a mid-range 2600K Sandy Bridge-based system can really push past the performance of a quad-core Socket 1366 processor. Now a little long in the tooth, it is time for a refresh. At its onset, Intel's Sandy Bridge Extreme platform was catered to the upper crust of the market, with the 6-core Core i7 3960X priced at $999. The Core i7 3930K was released at around $550, but Sandy Bridge-E was still lacking a "value" option for mainstream consumers. That is, until the release of the quad-core Core i7 3820, which is priced at just over $300. Socket 1155 Sandy Bridge processors, like the Core i7 2600K, have already proven to be potent performers, so what makes the step up to the SNB-E i7 3820 appealing for the X58 or Socket 1155 owner? Off the bat, it sees an increase in PCIe lanes from 16 to 40, support for PCIe 3.0, quad-channel memory with support for up to 64 GB of total system memory, increased L3 cache and computing performance, a bump in frequency to 3.6 GHz, Turbo Boost 2.0, a partially-locked chip for Sandy Bridge-style overclocking, and new instruction sets. Will the partially-locked nature of the Core i7 3820 present a large enough incentive on performance alone or will the Enthusiast have to step up to a 6-core chip to reap in the rewards of the Extreme socket and X79 chipset?
This Core i7 3820 sample arrives in a small black foam-padded box, sans all of the Intel retail packaging. While not indicative of what you will get at the store, it’s important to note that the Socket 2011 lineup all come without a cooling solution. The Second Generation Sandy Bridge-E Intel Core i7 3820 has 4 physical processor cores that support Intel Hyper Threading technology, which allows the chip to run up to 8 threads at a time. The CPU itself is built for use on motherboards using Intel's X79 chipset and LGA 2011 socket. This 32 nm chip has a die size of 294 mm2 or roughly two-thirds the size of the die used on the Core i7 3960X. It features 10 MB of onboard L3 cache, which is shared dynamically between the four processor cores and factory clocked to 3.6 GHz. Turbo Boost Technology 2.0 allows the Core i7 3820 to scale up to 3.9 GHz under certain workload scenarios. Much like the rest of the SNB-E lineup, the i7 3820 has an integrated memory controller that natively supports four channels of DDR3 1600 MHz system memory for increased bandwidth. Another unique feature of the Core i7 3820 is that it is a partially-unlocked chip. What this means is a multiplier that is locked to a maximum of 43x, initially limiting the potential overclock to 4300 MHz while using the default 100 MHz bclock. Using SNB-E’s exclusive "Gear Ratios" of 125 MHz and 166 MHz, however, it allows for some serious overclocking margins if you take the time to test the chip out. Additional top-line features are support for Intel AVX (Advanced Vector Extensions), SSE 4.1 and 4.2 instruction sets, and 40 PCIe lanes that meet the PCIe 3.0 specifications.
When compared to previous generation processors, the size of the LGA 2011 chip is absolutely huge to comparison to both the Socket 1366 and Socket 1155 chips. However with only four cores, no integrated graphics core, and 1.27 billion transistors on the Sandy Bridge i7 3820, the actual die size is smaller than the 3960X by about 33%, though it still retains the larger LGA 2011 package dimensions.
The Second Generation Core i7 Sandy Bridge Extreme processors are designed to work with a two-chip platform, with the bulk of the I/O on-die and the Platform Control hub taking care of the remaining functions. Coming off the Sandy Bridge-E processor are the four memory channels, each supporting a substantial increase in bandwidth to 12.8 GB/s. There are a total of 40 lanes of PCIe 3.0 graphics bandwidth, with each potentially carrying 1 GB/s of data, bi-directionally, and 8 GT/s (GigaTransfers per second) transfer rates on PCIe devices that support the speed. While not readily apparent on Intel’s specifications, a quick search reveals a good number of PCIe 3.0-compatible motherboards and graphics cards that support the updated interface, including the newly released Radeon HD7970. Multiple GPUs are supported in several configurations, which should improve multi-GPU performance. No longer will you have to sacrifice other PCIe device functionality due to a lack of PCIe lanes; eight lanes are now provided by the X79 PCH, on top of the 40 available from the CPU. A total of fourteen USB 2.0 ports, Intel Gigabit LAN, Intel HD Audio, and 6 SATA ports are attached to the X79 PCH as well.
Equipped with 2 fewer cores, 5 MB less L3 cache, and a billion less transistors than the 3960X, the Core i7 3820 looks to be a more direct comparison to the Core i7 2600K specification-wise, with the added advantage of a higher base clock speed of 3.6 GHz and quad-channel memory support. Let’s see if the Core i7 3820 is worthy of a step up to the extreme side and provides enough up-side to make the transition to Socket 2011.