Like the original Turion 64, the newer X2 version shares some of its roots with that of the desktop Athlon 64 X2 variant. Using two processing cores, each with its own dedicated Level 2 cache memory and integrating a System Request Switch and a Crossbar Switch that interface the processing cores with the on-die memory controller and HyperTransport interconnect, the basic structure largely remains the same.
However, in view of the imminent AM2 processor launch for the desktop systems that would utilize DDR2 memory instead of the standard DDR memory, the Turion 64 X2 has been designed with an integrated DDR2 memory controller instead. Not only that, but the once single-channel memory controller on the Turion 64 has been bolstered to a dual-channel controller, identical to that of the upcoming AM2 processors. Supports DDR2-400, DDR2-533 and DRR2-667 for up to 10.7GB/s total memory bandwidth.
As a result, the old Socket-754 (desktop-class) interface used on the original Turion 64 had to make way for a more optimized Socket S1 interface. Although Socket S1 only has 638-pins, the CPU packaging and interface is optimized for the processor's requirements in a notebook environment where AMD mentioned that there's reduced need for many grounding pins. Plus pin assignments and optimization brought forward reduced pin count needs even though the processor now has a dual-channel memory controller.
This also helped to reduce the Turion 64 X2 processor's overall package size and it is now smaller than its predecessor. Remember, space is premium on a mobile platform and thus this reduction would go the distance for an even more most favorable internal layout. While this might be a small blow to the DIY community hoping to get a desktop-class motherboard and procure a mobile-class processor for the best of performance, power consumption and thermal dissipation as has been the case for the original Turion 64 processors (which shared the Socket-754 interface among some desktop parts), you can bet on innovative and niche motherboard vendors like AOpen and ASUS to perhaps conjure a Socket S1 motherboard. Time will tell if this comes true.
Being a modern mobile part, AMD didn't just integrate two cores to the die and stop there. Extensive Multi-Core Power Management and Dynamic Thermal Management techniques have been integrated as well to ensure the Turion 64 X2 processor is as efficient and power conservative as possible while maintaining the performance legacy that the "X2" series have always delivered. You would expected that with double the processing cores integrated, the Turion 64 X2 would have a higher power consumption but instead, process improvements along the way have helped AMD maintain the exact same 35W Thermal Design Power (TDP) of the original AMD Turion 64 despite the same 90nm SOI fabrication technology. Also, AMD has tweaked the Turion 64 X2 a great deal in the power department that it is actually more power conservative than the original single core counterpart that actually draws less power under the various power management states. How does a 5% to 8% drop sound? A more complex processor and yet less power hungry ï¿½ you can't beat that combination. In fact, it's even better than the Intel Core Duo if the data specs published by both CPU vendors hold true.
With Multi-Core Power Management, AMD has also made the processing cores aware of their working (or non-working state) and automatically assert the halt command to conserve processing cycles. If system remains unused with no processes for either cores, the system can drop down into even deeper sleep states for better energy conservation. Even the HyperTransport bus is now power-optimized and can be powered down for further savings. Now, couple the Turion 64 X2 with a smart system chipset such as NVIDIA's upcoming mobile C51 offerings and a suitable display panel, the notebook might just offer NVIDIA's SmartDimmer technology which automatically dims the LCD in a bid to conserve some power while not having the screen completely blanked out when not in use (which may come across as an annoyance to many users). And yes, longtime readers of our articles will remember that this idea was first showcased in Computex 2004 and it is finally nearing maturity. ATI's just announced Radeon Xpress 1100 series for Turion 64 X2 Mobile Technology notebooks too have a similar feature that's known as Vari-Bright technology, but details of its workings nor demos have yet to be disseminated by the folks at ATI.
Note that the CPU's L2 cache is solely for each processor's use and it isn't shared like in the Intel Core Duo design. While the latter's advantage is a larger shared cache storage accessible by either core, the nature of the shared cache design does not allow both processors to access the core simultaneously and they have to arbitrate (take turns) to do so via a shared bus interface. The result? Higher cache latencies. This is not a problem of the Turion 64 X2 processor with each core's dedicated cache. Simpler in design with reduced latency penalties, the only limitation is reduced total processor cache storage since it is not a unified shared cache. Depending on the workload types, both AMD's and Intel's processors have their advantages in this design aspect.