A little over two years after the launch of its Core architecture with the now famous Core 2, Intel is grabbing the headlines again with another new processor architecture, Nehalem. On desktop PCs it comes in the form of the Core i7, previously known under the codename Bloomfield. Now launched, do they measure up?
Core i7 = Nehalem Desktop
It is commercialized as the Core i7 and with Nehalem architecture, introduced to you
in this report .
We won't go into the theoretical aspects of the architecture here then, as you can read up on that in the other article. To summarise the main points however, in contrast to Core architecture, Nehalem is a “monolithic” quad core architecture meaning that it isn't simply the fusion of two dual cores. Each of its cores has SMT technology that first appeared in Intel's Pentium 4 but wasn't present on the Core 2.
Previously part of the chipset, the memory controller has now been integrated in the processor and supports three channel DDR3. The caches have been reworked, still with 2x32 KB for the L1, but only 256 KB of L2 for each of the cores, which share an L3 cache of 8 MB. Nehalem also uses a new processor bus, the QPI, which is twice as fast and will allow server versions to interconnect between different processors and their memory controllers. Nehalem has also introduced Turbo mode, which allows you to accelerate processor frequency automatically, within in the limit of its TDP.
In the course of this article, we study the impact of these different advances in practice, so as at last to be able to compare the Core i7 with the current range of processors.
3 CPU, 1 chipset, 1 Socket
Intel has now launched 3 versions of the Core i7:
Core i7-965: Extreme Edition: $999 (3.20 GHz)
Core i7-940: $562 (2.93 GHz)
Core i7-920: $284 (2.66 GHz)
In addition to processor speed, these CPUs mark themselves out by the frequency of the “uncore” part and the speed of the QPI: 2.66 GHz and 6.4 GT/s on the 965, against 2.13 GHz and 4.8 GT/s for the 940 and 920. Only the first parametre has any real impact on performance in practice. With the Core i7-965 Extreme Edition moreover it is possible to modify the multiplier.
They all use the new LGA1366 Socket and require new motherboards and fixations for the cooling system. They are all based on the only chipset able to support these processors now, the X58. It is made up of an IOH, the X58, which links the QPI bus to the processor, as well as 36 PCI-Express lanes that can be used in 1x16, 2x16 and 4x8, among others.
All motherboards based on the X58 support CrossFire, as Intel has paid a license for this, but Intel and NVIDIA have not been able to reach an agreement on the SLI licence. SLI support therefore goes on a motherboard by motherboard basis as this is dependent on certification by NVIDIA. At this time, all manufacturers seem to have signed up for their X58s, with the exception of Intel.
