It’s been a little more than a year since Intel launched the first Nehalem-based Core i7 processors—the pathbreaking Core i7 920 and 940 that came in the LGA 1366 package and featured Hyper-threading and on-die memory controllers. Then we saw the Core i7 and Core i5 processors in LGA 1156 packages (codenamed Lynnfield) that were within the reach of mainstream audience. These featured on-die PCIe controllers too, and used the budget-friendly P55 chipset. The time to shift gears has now come again. Following its ‘Tick-Tock’ model of delivering a new architecture followed by shrinking the process technology, the latest by Intel is shrinking the Nehalem to a 32 nm process (codenamed Westmere) along with introducing a load of new features.
Say hello to Clarkdale
Clarkdale is the codename for the new dual-core Westmere-based CPUs. They feature the same cache sizes as those in Nehalem—32 KB L1 cache per core, 256 KB L2 cache per core and a large 4 MB L3 cache shared among both the cores. The dual-core Westmere die measures 81 mm2 and packs 383 million transistors which is less than half the size of a quad-core Lynnfield but equally dense due to the process shrink. But unlike Lynnfield, the memory and PCIe 2.0 controllers aren’t on-die. Instead, they’re packed in the second 45 nm die along with a graphics controller. This is actually larger than the CPU die and has only 177 million transistors. The dies are interconnected by a Quick-Path Interconnect (QPI) link.
Now for the interesting part! These CPUs support Hyper-threading, which means each core is capable of processing two threads simultaneously. So these CPUs will show up as quad-cores in the Windows Task Manager. Like Nehalem, Turbo Boost is also a part of the feature set. This will allow the cores to run faster than their base speed depending on the workload, voltage and temperature.
The most interesting feature is the on-package GPU which is called Intel HD Graphics. Intel has done away with the numbering conventions to make things simpler. The new graphics engine is DirectX 10 capable and supports a wide range of connectivity including HDMI and DisplayPort. Its ability to decode high definition content (AVC, VC-1 and MPEG-2) along with support for bit streaming Dolby TrueHD and DTS-HD Master Audio via HDMI makes it an excellent processor for home theater PCs. Intel has also added six new instructions (AES-NI) to speed up applications that use the AES algorithm for encryption and decryption. This will benefit individuals and businesses for whom data security is critical.
Seven Clarkdale processors are officially launched across the Core i3 and i5 lines, all dual-core with Hyper-threading. The only differentiator is Turbo Boost, which is only found in the Core i5s. Further, the i5-661 and 660 have the same core speed but the former has a slightly faster GPU (900 MHz