Clarkdale: 2 cores and 4 MB of L3 at 32nm and a 45nm chipset!After integrating the memory controller into the processor with the Core i7 Bloomfield LGA1366s, Intel went even further with the Core i7/i5 Lynnfield LGA1156s as these also included the PCI-Express controller. The northbridge such as we’ve known it up to now was therefore completely integrated onto the chip.
With these new Core i5/3s engraved at 32nm, codename Clarkdale, Intel has gone back in the opposite direction. While the northbridge is still included in the LGA1156 packaging, it has now been dissociated from the processor as such and what we have are two distinct dies:
- The CPU, or 383 million transistors engraved at 32nm on 81mm²
- The northbridge or 177 million transistors engraved at 45nm on 114mm²
On the CPU side then, we sort of have half a Lynnfield as the number of cores has dropped down from 4 to 2 (though still with hyperthreading) and the L3 cache from 8 to 4 MB.
The other chip is for its part a separate northbridge with:
- A PCI-Express controller with 16 lanes at 1x16 or 2x8
- A dual channel DDR3-1333 memory controller
- A DX10 graphics controller
Intel hasn’t given any information on the type of bus linking the two chips. The gain given by the 32nm engraving is obvious. If you compare with a Core 2 E7xxx, based on a Penryn die (2 cores, 3 MB of L2 cache) which has 228 million transistors on 82mm². On an almost identical surface, Intel has been able to place 68% more transistors!
Intel has made the most of the move to 32nm to carry out architectural changes with 6 new SIMD instructions, called AES-NI (Advanced Encryption Standard New Instructions) by Intel. 4 of them have been designed to acclerate encrytion and decryption operations and 2 others accelerate the key extensions procedure.
The seven Clarkdales
There are no fewer than 7 processors based on the Clarkdale chip. This means there are now 10 LGA1156 processors in the Core and Pentium ranges:
The Clarkdales are shared across 3 ranges, the Core i5s being the full models and the Core i3s without turbo. The Pentium G9650 doesn’t have hyperthreading either and only 3 MB of cache and an IGP that’s 200 MHz down.
Note the rather original 661 model in the Core i5 range. It has an IGP clocked at 900 MHz against 733 MHz for the rest of the range and its TDP is up to 87W as against 73W. We’ll tell you right away, we’re having trouble understanding the rationale of this processor, unless it’s to show the IGP in its best light.
Note that while the Clarkdales are compatible with P55 Express motherboards, you need a motherboard based on an H55 or H57 chipset to use the integrated IGP (the H55 being a lite H57 without RAID, with 12 USBs instead of 14 and 6 PCI-E lanes instead of 8). With these chipsets, the Clarkdale’s PCI-Express controller is limited to the 1x16 mode and can’t be at 2x8, a purely marketing limitation.