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Intel Core 2 Duo X6800 and E6700 Review - Conroe is Here

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Subject: Processors
Manufacturer: Intel
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Core 2 Duo Architecture

Introduction


The wait is nearly over.  If you are reading this, then the NDA on the Conroe processor (known throughout the world now as the Intel Core 2 Duo) has lifted and the world is on fire with performance numbers and evaluations.  Even though we have had Conroe here at PC Perspective for some time, and we have had the chance to play with it on NVIDIA nForce 590 boards, 975X boards and 965 boards, I am still excited to present the information here in this review today. 


Let's first take a quick walk through the technology and history of the Conroe and Intel's new Core Architecture.


Core 2 Duo - Intel's Core Architecture


At this past spring IDF in San Francisco, Intel shared with the world much of the details behind the new Intel Core 2 Duo processors powered by Intel's Core Architecture.  The name of the technology behind Conroe, Merom and Woodcrest, which are all codenames for processor cores, was officially named "Core Architecture" and is the basis for all the hype that has been building at Intel for months. 


Let's see what makes the Core 2 Duo processors tick by glancing at the architecture below the hood.



Quickly stepping through these features, we first hit on the wide dynamic execution.  While past AMD and Intel architectures ran on a three instructions per clock design, Intel's Core 2 Duo can act on four instructions simultaneously.  If the improved Intel macro-fusion does its job properly, the Core 2 Duo can actually perform up to five instructions per cycle.  This macro-fusing technology allows the processor to take two seperate instructions, combine them into one single instruction that the CPU can handle, and perform them both at the same time, effectively increasing the amount of work that can be done.


Intel's advanced digital media boost describes an increase in the amount of SSE calculations done per cycle in the core. With support for 128-bit multiply, add, store and load operations, the Core 2 Duo CPUs can then combine instructions to possible do more than five calculations per cycle, though this case isn't nearly as frequent.


The ability to reorder memory operations for better performance is called smart memory access on the new Core 2 Duo processors.  Intel's architecture has the ability to determine whether or not a memory load is going to depend on one of the preceding stores (that would essentially change the data this Data X load is going to receive).  If it does not, the architecture can move the command up to improve system performance.  If it does, the architecture has to leave it alone to prevent any kind of data accessing errors.  When this works, it can improve the out-of-order execution speed pretty dramatically and best of all, the results are transparent to the software and don't require any compiling or coding.



Intel 'Conroe' Core 2 Duo Die


Advanced smart cache is the term given to Intel's dynamically allocated L2 cache system in place on the Core 2 Duo processor.  The amount of L2 cache that is being controlled by either core can be adjusted dynamically when one core is in need of more of it than the other.  If only a single thread is being executed in the operating system, the primary core can take more of the L2 cache and use it to lower the memory latency hit, thus preventing the 'cache thrashing' when cache is full and the CPU has to go to main system memory.  This can also allow for easy data sharing between cores on the CPU.


Finally, Intel's intelligent power capability is designed to allow the system to power down and slow down as much of the processor as possible when unneeded in order to save on power and produce less heat.  First they have integrated an ultra fine grained power control system that allows them to turn off portions of either core that are not in use.  Another way Intel's engineers saved power was by allowing the internal busses between the ALUs and other units to be turned down to the data size of the information they are working on.


If you would like even more details, diagrams and information on the Core Architecture technology, you should definitely check out my article from IDF that covered this in much greater detail than we have here.

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