I don't know how true this is...but according to wikipedia hyperthreading is disabled in the current i5's...you might want to investigate that first...
Lynnfield
Main article: Lynnfield (microprocessor)
On September 8, 2009, Intel released the first Core i5 processor: The Core i5 750,[1] which is a 2.66 GHz quad-core Lynnfield processor with Hyper-threading disabled. Lynnfield Core i5 processors have an 8 MB L3 cache, a DMI bus running at 2.5 GT/s and support for dual-channel DDR3-800/1066/1333 memory. The same processors with different sets of features (Hyper-Threading and other clock frequencies) enabled are sold as Core i7-8xx and Xeon 3400-series processors, which should not be confused with high-end Core i7-9xx and Xeon 3500-series processors based on Bloomfield.