It has been a year since the first Intel processor based on the Nehalem architecture appeared on the market, branded as Core i7, targeting the high-end of the market. The Core i5 brand followed in September 2009, targeting the mid-range.<\/p>\n
As is common practice in the hardware industry, branding tends to be splashed across a variety of different products, each with different features and capabilities. In order to clarify what one can expect from a processor, it is best look at the processor code name, as this will be a clear indicator of its feature set.<\/p>\n
Below we take a look at the significant features of Nehalem based CPUs, and the currently available desktop derivatives – the Bloomfield and Lynnfield processors.<\/p>\n
Nehalem<\/strong><\/p>\n Notable technology improvements coming from the Nehalem architecture include TurboBoost – which enables the processor cores to dynamically increase their clock speed – and the reimplementation of Hyper-threading (HT) – which enables each of the four cores to process two threads simultaneously, effectively providing the functionality of eight cores.<\/p>\n To add to the confusion, HT is only implemented on processors carrying the Core-i7 brand, meaning that Lynnfield based i7 chips have HT enabled. Clearly Intel considers HT to be a high-end feature.<\/p>\n On the legacy LGA 775 (Socket T) motherboards, the memory control function was handled by the north bridge, which communicated with the RAM and CPU via the Front Side Bus (FSB). <\/p>\n This changed with the Nehalem based CPUs, which introduced an on-die memory controller, and with that came the need for two new sockets – the LGA 1156 (Socket H) and LGA 1366 (Socket B). On-die memory control was not an altogether new concept though, having already been implemented by AMD for a number of years.<\/p>\n Bloomfield – LGA 1366<\/strong><\/p>\n The Bloomfield processors use the LGA 1366 socket, and were first released in November 2008. Currently the Bloomfield based Core i7 range includes the i7-920, i7-930, i7-940, i7-950 and i7-960. Under the Core i7 Extreme brand are the i7-965 and i7-975 – these chips offer unlocked core multipliers.<\/p>\n A new QuickPath Interface (QPI) has replaced the legacy FSB between the CPU and Input\/Output (I\/O) hub, providing a massive 25GB\/s direct point-to-point connection.<\/p>\n Bloomfield processors are supported by the X58 I\/O hub, which handles up to 36 PCI-E 2.0 lanes. A single GPU can potentially demand 16GB\/s of bandwidth. Coupled with the X58’s 25GB\/s QPI interface to the processor, the configuration provides more than adequate bandwidth for multiple CPU or GPU configurations.<\/p>\n The Bloomfield range uses a triple channel (192 bit wide) memory controller, supporting DDR3 RAM. Operating at a standard 1066MHz, one can achieve 25.6GB\/s peak bandwidth rates. Of course, these clock speeds can be increased, but at the risk of damaging the on-die memory controller.<\/p>\n Lynnfield – LGA 1156<\/strong><\/p>\n In September 2009, along with the launch of the Core i5 brand, came three new Nehalem based Lynnfield processors, and the LGA 1156 socket. The Lynnfield range currently includes the i5 750, i7 860 and i7 870.<\/p>\n Supporting the Lynnfield processor is the P55 chipset, which has done away with the need for combinations of I\/O hubs, north bridges and south bridges. This new system has been dubbed the Platform Controller Hub (PCH).<\/p>\n Lynnfield processors lack QPI, and the PCH interfaces with the CPU using the older Direct Media Interface (DMI), which operates at 2GB\/s. Intel’s reason for this move was to position the Lynnfield as a more affordable mid-range CPU.<\/p>\n Since DMI does not provide enough bandwidth to handle PCI-E 2.0, this function has also been moved on to the CPU die. The Lynnfield supports up to 16 PCI-E 2.0 lanes. The PCH therefore only handles peripheral interfaces, since the traditional core functions of the north and south bridges have been moved to on-die.<\/p>\n The Lynnfield on-die memory controller operates DDR3 in dual channel mode (128 bit wide), and when using 1333MHz RAM, one can achieve a peak bandwidth of 21.2GB\/s.<\/p>\n Final thoughts<\/strong><\/p>\n The Bloomfield processors are currently aimed at the high end of the desktop market. An entry-level Bloomfield variant – the Core i7 920 (coming in as low as R2,645.94 on PriceCheck) – combined with a decent motherboard such as the Asus Rampage 2 Gene (R2,765.01 – R3,074.58) will make for powerful workstation or gaming system.<\/p>\n Lynnfield processors are targeting the mid-range market. Currently the Core i5 750 (R1,955.68 – R2,155.00 on PriceCheck) is the only i5 branded chip on the market, and when coupled with a motherboard such as the Intel DP55KG (R2,083.00 – R2,306.88 on PriceCheck), one has themselves the basis of a powerful mid range desktop PC or gaming rig.<\/p>\n To get the most out of a Bloomfield system, one really needs to intend running multiple CPUs and\/or GPUs, positioning the systems as high-end workstation or gaming platforms. A Lynnfield system will be more than adequate as a general purpose workstation, and one can even build a rather powerful gaming rig, although dual discrete GPUs may suffer, being forced to operates at 8GB\/s per slot.<\/p>\n