Intel Nehalem processor

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Greg Corke takes a look at Intel’s impressive new Nehalem architecture, brought to market in the Core i7 and Xeon 3500 / 5500 Series processors, which feature a range of brand new technologies that will help push the boundaries of CAD and visualisation in 2009.

Alot has been happening in the world of processors over the past few months. The big news is that Intel has launched two new chip families based on the brand new Nehalem architecture, which represents one, if not the biggest architectural shifts in Intel processors for ten years. The products in question are the Core i7 and the Xeon 3500 / 5500 series, but it is the Xeon processor that is taking centre stage in the new product ranges from all the major workstation manufacturers, like Dell, HP, Fujitsu Siemens and Lenovo. Core i7, on the other hand, has only been picked up by the specialist workstation builders, such as CAD2, Xworks, Boxx and Scan.

There are many similarities between Core i7 and Xeon, and the most important architectural features are supported on both platforms. Let’s first have a look at what these are and what they mean for CAD and design visualisation applications and then follow this up with the differences between the Core i7 and Xeon.

Faster memory

At the heart of this new architecture is a change in the way the chip accesses memory. Instead of the CPU communicating with the memory via the Front Side Bus, Core i7 and Xeon 3500 / 5500 can receive data directly from the system RAM. If this sounds familiar, that’s because it is, as AMD pioneered this integrated controller strategy with its Athlon & Opteron processors a few years back.

With Intel’s Front Side Bus architecture, which is used on the Core 2 Duo and many generations before, there was a lot more latency when accessing memory. Now with Core i7 and Xeon 3500 / 5500, applications that access a lot of memory, frequently, will see a benefit. This is why AMD’s Opteron has remained a popular choice with certain users of simulation software, despite it being slower in most mainstream applications.

The other change in the memory architecture is that the new memory controller has three channels to the RAM which means that Core i7 and Xeon 3500 / 5500 systems will work best when memory modules are in multiples of three, as opposed to two. This means we are likely to see workstations with 3GB, 6GB and 12GB memory instead of the usual 2GB, 4GB, and 8GB.

HyperThreading

All Core i7 and Xeon 3500 / 5500 CPUs have four cores as standard, but they also feature a technology called HyperThreading, which simulates additional threads so each chip actually has eight logical cores. HyperThreading first came to market with the Pentium 4, but was abandoned for the Core 2. It uses spare CPU cycles on each physical core to simulate additional cores, and these can be seen when you bring up the Windows System Performance Dialogue.

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The technology only works with certain multi-threaded applications, and can cause confusion when a process assigns itself to a ‘logical core’ even when there is a physical core sitting around doing nothing. Our tests show that it does make a small but significant difference in rendering applications such as 3ds Max, but won’t benefit most CAD / BIM applications directly.

Turbo Mode/Overclocking

Core i7 and Xeon 3500 / 5500 feature a new Turbo Mode technology that can automatically adjust the speed of the cores dynamically. The chip can literally switch off those cores that are not being used and channel additional power to the remaining cores.

Intel claims that for single threaded applications (of which most CAD applications are) the speed of a single core can be boosted by around 300MHz-400MHz.

While Turbo Mode can dynamically adjust the speed of the CPU, specialist workstations manufacturers are looking to get more out of each piece of silicon by overclocking or permanently increasing the speed of chips.

With Core i7 and indeed Core2 Duo, Intel has built in a lot of headroom into its chips. Some say this is because it has no real incentive to sell faster CPUs at this moment in time, because it could jeopardise future sales if the performance leap is too high.

The good news is that those in the know are able to get more out of the chips for no additional cost, overclocking them by around 20 percent.

Overclocking has never really been used in the CAD sector, simply because reliability has been deemed more important than performance. However, even with standard cooling solutions, specialist workstation vendors are now offering overclocked systems. But this is not pony tailed geeks in bedrooms with soldering irons, the system builders are extremely confident that the silicon will not be damaged by overheating and this is being backed up with three year warranties.

At AEC, we don’t expect overclocking to be embraced wholeheartedly by customers, simply for fear of unreliability. However, if confidence grows, and specialist workstation manufacturers continue to push overclocked systems, it will be very interesting to see what impact this has on the Tier One Vendors as the likes of HP, Dell and Lenovo will have to play by the rules and ship systems at Intel’s published speeds.

Core i7 vs Xeon

The main difference between Core i7 and the new Xeon is that that Xeon workstations can support two physical processors. This means users have access to a staggering 16 cores (if you include HyperThreading), which is an incredible amount of power to have on the desktop. However, this is only likely to be of real interest to users of rendering applications like 3ds Max, where accelerating performance can have a huge impact on using visualisation throughout the design process. N.B. There are actually two types of Xeon (Nehalem) processors, the Xeon 3500 Series and Xeon 5500 Series and it is only the Xeon 5500 Series that supports dual socket.

In addition to offering a dual processor capacility, both the Xeon 3500 and 5500 Series supports ECC (Error Correcting Code) memory for better accuracy.

Conclusion

The Nehalem architecture is a huge leap forward for Intel, introducing a number of new technologies, which not only improve efficiency in multi-threaded applications but enhance performance in single threaded applications. As with any new technology, prices are high at the moment but expect significant cuts later this year.

www.intel.com

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