www.anandtech.com/cpuchipsets/showdoc.aspx?i=2397&p=2
A Look at AMD's Dual Core Architecture Even Intel will admit that the architecture of the Pentium D is not the m ost desirable as is two Pentium 4 cores literally glued together. The t wo cores can barely be managed independently from a power consumption st andpoint (they still share the same voltage and must run in the same pow er state) and all communication between cores must go over the external FSB.
Intel's Pentium D dual core architecture Any communication between the two cores has to be done over the external FSB, and obviously, core-to-core communication over an external bus is s low. It particularly doesn't make sense, since the two cores are on the same die. Even the 65nm successor to the Pentium D (Presler) will have this same limitation. AMD's architecture is much more sophisticated, thanks to the K8 architect ure's on-die North Bridge. While we normally only discuss the benefits of the K8's on-die memory controller, the on-die North Bridge is extreme ly important for dual core. Instead of having all communication between the cores go over an external FSB, each core will put its request on th e System Request Queue (SRQ) and when resources are available, the reque st will be sent to the appropriate execution core - all without leaving the confines of the CPU's die. There are numerous benefits to AMD's imp lementation, and in heavily multithreaded/multitasking scenarios, it is possible for AMD to have a performance advantage over Intel just because of this implementation detail alone.
The one limitation that both AMD and Intel have is bandwidth. In order t o maintain compatibility with present day Socket-940 and Socket-939 moth erboards, AMD could not increase the pincount of their dual core process ors. The benefit is that AMD's dual core CPUs will work in almost all S ocket-940 and Socket-939 motherboards (more on this later), but the down side is that the memory bus remains unchanged at 128-bits wide and suppo rts a maximum memory speed of DDR400. So, while single core Athlon 64 a nd Opteron CPUs get a full 64GB/s of memory bandwidth, today's dual cor e CPUs are given the same memory bandwidth to share among two cores inst ead of one. AMD's solution to the problem will come in the form of DDR2 and a new soc ket down the road, but for now there's no getting around the memory band width limitations. Intel is actually in a better position from a memory bandwidth standpoint. At this point, their chipsets provide more memory bandwidth than what a single core needs with their dual channel DDR2-66 7 controller. The problem is that the Intel dual core CPUs still run on a 64-bit wide 800MHz FSB, which makes Intel's problem more of a FSB ban dwidth limitation than a memory bandwidth limitation. Backwards Compatibility Intel's dual core Pentium D and Extreme Edition won't work in any previou s motherboards, but as we mentioned at the start of this article, AMD ha s more bang. Here, the additional bang comes from the almost 100% backw ards compatibility with single-core motherboards. here's the breakdown: - On the desktop, the Athlon 64 X2 series is fully compatible with all S ocket-939 motherboards. If the motherboard does not support 90nm Opterons then you a re, unfortunately, out of luck. For desktop users, the ability to upgrade your current Socket-939 motherb oards to support dual core in the future is a huge offer from AMD Whil e it may not please motherboard manufacturers to lengthen upgrade cycles like this, we have never seen a CPU manufacturer take care of their use rs like this before. Even during the Socket-A days when you didn't have to upgrade your motherboard, most users still did because of better chi psets. AMD's architectural decisions have made those days obsolete. The next generation of dual core processors will most likely need a new mot herboard, but rest assured that you have a solid upgrade path if you hav e recently invested in a new Socket-939 desktop system or Socket-940.
Priority Electronics- Laptop Battery Store Online seller of notebook batteries, accessories, and parts, featuring lo w prices for all major brands, such as, Dell, Sony, IBM, Toshiba, Compaq , HP, Gateway and more.
com We have what you are looking for in stock & ready to ship at a great pric e! Computers, Notebooks, Monitors, Digital Cameras, CPU's, Memory, Mothe rboards, Barebone kits, Networking, Video, & more at the best values.
Remote Access - Remote PC Remote PC offers secure remote access to your desktop from anywhere with an internet connection. Great for mobile professionals and office to hom e connectivity.
Velocity Micro proves a computer is more than the su m of it's components. Experience our powerful Velocity Generator configu ration tools to let us build your dream system!
File replication and content synchronization - RDS One-to-one, scheduled file replication and content synchronization for cr oss platform replication on Windows & UNIX.
|
http://csua.com/feed/