Intel 2nd Gen (Sandy Bridge) i7 vs. i5

The Intel Second Generation i5 chip -- also known as the Sandy Bridge i5 -- has been in our sweet spot in terms of price versus performance for quite a while.  You can purchase a powerful laptop with this chip -- for about $550-$600 (and get your favorite combination of RAM, hard-drive, and other specs).  That is a great value.

However, laptops with the more powerful 2nd generation i7 chip have stayed stubbornly in the $700-$900 range.  We expect prices to drop, however, with an improvement in specs due to Intel's new Ivy Bridge chip set, due out in April 2012.  If you had to get a laptop now, is the i7 really worth the extra bucks?  When prices drop, how much better is the i7 versus the i5?

We decided to investigate:

• If you are a "light" laptop user (browse the net, read news, check email), the 2nd generation i3 will be a great value and serve your purposes.
• However, if you are interested in performance, the i7 is definitely more powerful than the i5, which is more powerful than the i3.  The number / name of the chips i3 (***), i5 (****), and i7 (*****) -- as well as the star ratings -- are indicative of processor power.  Below are some details.
• Number of Cores:  i3 chips are dual core, while most i5 and i7 chips are quad core.  NOTE that for laptop chips, i7 Quad Core CPUs are indicated by a Q (for example, i7-2630QM)
• Hyper-Threading: normally, one core can serve only one thread.  Thus, a dual core chip can normally only have two threads.  However, Intel introduced hyper-threading, which allows cores to serve multiple threads.  Many i3 dual core chips use this technology, so the two cores can have four threads.  Note that some i5 quad core chip sets do not support hyper-threading, which means that four cores could be served, the same number of many i3 dual core chip sets that allowed two threads to be served!  The i7 chip set benefits from both the quad core technology and hyper-threading -- so this is one area where the i7 particularly shines (8 threads!).  
• Cache Size:  Many computer enthusiasts know that RAM is an important feature to study when purchasing a new computer.  Computers store data in RAM, which it is able to access faster than reading data from the hard-drive.  Cache is similar to RAM, except that it is even faster because the cache is built into the processor.  (RAM minimizes hard-drive access time and Cache minimizes RAM time by storing frequently used data in cache).  The i3 has 3MB of cache, while the i5 has 6MB, and i7 has 8MB.   
•   Intel Turbo Boost:  when the pc recognizes the need for additional computing power, the i5 and i7 chips are equipped with this turbo boost technology that allows it to dynamically increase its clock speed (as a function of the number of cores, processor temperature, and estimated power consumption).  

We will be saving our money for an i7 laptop -- and will be keeping an eye on the Intel Ivy Bridge chip -- which looks very promising!

Some good sources:
http://www.pcworld.idg.com.au/article/386100/what_difference_between_an_intel_core_i3_i5_i7_/?pp=2

And introducing the Intel Ivy Bridge chip set:
http://www.tomshardware.com/news/Benchmarks-Intel-Ivy-Bridge-CPU-sandy-bridge,14144.html
http://www.anandtech.com/show/5174/why-ivy-bridge-is-still-quad-core


Ivy Bridge -- said to cost the same as Sandy Bridge and perform about 10% better...
http://us.battle.net/wow/en/forum/topic/4062878026