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Intel Sandy Bridge Mobile Processors Explained

The long wait for the new, mobile Sandy Bridge processor equipped laptops is nearly over. Most of the large system vendors have announced their new lines, and systems are starting to actually ship.

These machines will have significantly better performance and better battery life than their 2010 vintage predecessors.

Below is an example of the new Sandy Bridge logo, with the gold band that looks like it is a step. Knowing that logo will help you quickly spot Sandy Bridge machines in a store.

2nd Generation Intel® Core™ i7 Processor Logo

Below is the old Core i7 logo.

Intel® Core™ i7 Brand Logo

When you are ordering a customized laptop, one important choice you have to make (and live with for the life of the machine in most cases) is what processor you want to get. After all, it is pretty easy to add RAM to a laptop (if it is not already maxed out) and to upgrade to a large, fast solid state drive (SSD).

If you are relatively hardware savvy, it is usually much cheaper to order your laptop with a small amount of RAM, and a small, slow hard drive, and then buy more RAM and a faster hard drive or SSD yourself from somewhere like NewEgg. This also gives you a chance to do a fresh install of the operating system on a new hard drive or SSD, leaving the original drive intact.

Here are links to the product pages for each of these five mobile Sandy Bridge processors:

Dual-Core (plus hyper-threading)

Intel Core i5-2520M Processor  (3M Cache, 2.50 GHz)

Intel Core i5-2540M Processor (3M Cache, 2.60 GHz)

Quad-Core (plus hyper-threading)

Intel Core i7-2720QM Processor (6M Cache, 2.20 GHz)

Intel Core i7-2820QM Processor (8M Cache, 2.30 GHz)

Intel Core i7-2920XM Processor Extreme Edition (8M Cache, 2.50 GHz)

Price/Performance Analysis

Table 1 shows these five processors, with their price, my estimate of their relative CPU performance, and a simple calculation of the price per performance point.

Model Price Relative Performance $/Perf
Core i5-2520M $225 100 2.25
Core i5-2540M $266 104 2.56
Core i7-2720QM $378 176 2.14
Core i7-2820QM $568 202 2.81
Core i7-2920XM $1096 220 4.98

Table 1

For example, the Core i5-2520M has a base clock speed of 2.5GHz, while the Core i5-2540M has a base clock speed 0f 2.6GHz. Both processors have the same size L3 cache, and their relative Turbo Boost speeds only differ by 100MHz. Finally, both processors have the same DDR3 memory speed of 1333MHz. These two processors are basically identical, except for a 100MHz clock speed difference.

Giving the Core i5-2520M an arbitrary baseline performance score of 100, my paper analysis would give the Core i5-2540M a 4% increase due to the 100MHz increase in clock speed, so the Core i5-2540M gets performance score of 104.

I use a similar methodology for assigning a performance score to the other three Sandy Bridge processors listed in Table 1. The Core i7 processors are all quad-core, plus hyper-threading. They have differing L3 cache sizes and Turbo Boost speeds.

According to this analysis, the sweet spot for price/performance is definitely the entry level quad-core, Core i7-2720QM with a $2.14/performance point figure. The “top of the line” Core i7-2920XM, which is an Extreme Edition part, is not a good deal at all. You would be far better off to spend that extra money on a fast 6Gbps SSD.

This picture shows the main specifications and features for these five processors:


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