Introduction
The processor war between AMD and Intel has turned into a rout lately, and a stream of impressive Athlon 64 FX and X2 dual core models has helped keep it that way. There was really no true performance battle, as AMD held a significant lead in virtually every category, and the Athlon 64 X2 line grew extremely popular with desktop users. The situation was looking so grim that Intel was literally forced to fight back the only way it could, by drastically cutting prices on their Pentium D line, and offering a better price-performance mix to entice buyers. Well, those days will soon be just a bad memory, and with the debut of the Core 2 architecture, Intel is moving in an entirely new direction by combining ultra high performance and attractive pricing with industry-leading power and heat specifications. This is the real deal, and we cannot remember a processor that arrived with such intense fanfare and extremely high expectations.
The Core 2/Conroe Architecture
The Core 2 is a departure from the old Intel NetBurst architecture, and its Conroe core offers a best of breed combination of various Intel processor features, from the Pentium D to the Core Duo. Intel realized they would need to pull out all the stops to beat AMD, so there is no holding back in terms of overall features, support or bus speeds. The Core 2 offers dual core processing, clock speeds of up to 2.93 GHz, up to 4MB of shared L2 cache, and a 1066 MHz front-side bus. The core has also been redesigned to support a higher number of instructions per cycle, or what Intel refers to as Wide Dynamic Execution.
The Advanced Smart Cache is an interesting feature, and instead of offering dedicated L2 cache per core, the Core 2 processors share the L2 cache, which is then dynamically allocated based on workload. This is an intriguing design, and its flexibility means that in scenarios where a single core is getting most of the workload (like in many games) then the entire 4MB of L2 could theoretically be made available, just as in multi-processing environments, the dual core optimized L2 ensures both flexibility and high performance. The Conroe's L2 bus is also fully 256-bit, as opposed to the 128-bit L2 cache of the Athlon 64 FX and X2. The L1 cache has also been increased to 32KB instruction/32KB data caches per core (from 16KB/16KB on the Pentium D), and each has 8-way associativity. The Athlon 64 FX/X2 has larger 64KB/64KB L1 caches but these are only 2-way.
The Conroe core includes support for Intel SpeedStep technology, and in an attempt to lower power and heat requirements, it emulates a mobile processor by lowering the multiplier when idle or in low usage. In the case of the Core 2 Extreme and Duo processors we reviewed, that amounted to a 1.6 GHz clock speed at idle. The Conroe can immediately fire up at full speed and match the system load. Core voltages can also be lowered through similar techniques, such as Intelligent Power Capability, which can turn computing functions on and off when needed, in order to fully maximize power efficiency.
Conroe also features Smart Memory Access, which uses pre-fetch algorithms and prediction mechanisms to speed up data transfers from system memory and into the L2 cache. This improves out-of-order execution and increases instruction throughput and overall bandwidth. Intel's Advanced Media Boost increases the execution rate of SSE instruction, and effectively doubles the throughout on a clock-for-clock basis compared to previous generation Intel processors. The Conroe core also includes support for SSE4, Intel Virtualization Technology, Intel EM64T, and Execute Disable Bit.
The Core 2 Extreme X6800 & Core 2 Duo E6700 Processors
The Conroe has made its appearance in the Core 2 Extreme and Core 2 Duo lines, and each sports the same basic architecture. The Core 2 Extreme X6800 is targeted at the ultra high-end of the market, with enthusiast gamers being an important segment, and is designed for those who want the absolute fastest desktop performance. In the past, this was part truth and part Intel marketing, but with the Core 2 Extreme, you can take that statement to the bank. The Core 2 Extreme X6800 supports the LGA775 socket, is clocked at 2.93 GHz, features 4MB of L2 cache, and runs on the 1066 MHz front-side bus. The Core 2 Extreme X6800 has a TDP (Thermal Design Power) of 75W, or slightly higher than the 65W of the Core 2 Duo and displayed core voltages in the 1.2V range. It is also the only Core 2 Extreme model being released in this wave.
The processor's bus ratio lock (or as Intel calls it, "overspeed protection") has been removed, allowing users unprecedented overclocking control, and the 2.93 GHz lock speed is the highest for any Core 2 processor. The only strange thing is that the higher clock speed and an unlocked multiplier will be its main selling points, and unlike previous Extreme Edition models, there are no extras like Hyper-Threading to differentiate it from the base line. Honestly, HT was a double-edge sword, offering enhanced performance in some areas, yet no improvement in others, so it will not be missed that much. It also added to overall core power and heat, so with Intel employing a top-to-bottom Core 2 architecture, HT would not be a great mobile solution.
The Core 2 Duo is the mainstream processor line also supporting the LGA775 socket, and includes two distinct segments. The Core 2 Duo E6700 (2.66 GHz) and E6600 (2.4 GHz) are the performance models, each including a full 4MB of L2 cache and running on the 1066 MHz front-side bus. The entry-level Core 2 Duo E6400 (2.13 GHz) and E6300 (1.86 GHz) not only have lower clock speeds, but also include only 2MB of shared L2 cache. All Core 2 processors use the 1066 MHz bus, including the 2MB variants. These four Core 2 Duo models feature a TDP (Thermal Design Power) of 65W and a core voltage of approximately 1.2V.
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