The 45nm C2D and C2Q have been around for a while now and they really made a huge difference to the Core 2 line of CPUs.  The smaller process brought with it lower voltages and lower temperatures and gave us higher overclocks.  Just about everyone could take their new C2D CPUs and run them at 4Ghz and beyond.  Intel has just recently released a new top dog to their 45nm C2D line, the E8600.  The E8600 brings with it more stock MHz and the magical 10 multiplier.  It also brought with it a new stepping.  When people started looking at the CPU-z screen, they noticed an E0 where the C0 used to be.  The new stepping also made its way down to the E8400 and E8500.  Today we are going to look at identifying the new cores and some overclocking.

Changes

- CPUID will change from 0x10676 to 0x1067A
- Power Status Indicator (PSI) is supported
- PECI implementation change
- New instructions added - XSAVE/XRSTOR
- New ISA extension for save/restoring context of x87, SSE, and future processor state
- New feature added - ACNT2
- Improved mechanism for determining processor utilization. To be used for more efficient P-state determination.
- Package change to Halide free package 

For the new stepping you should not need a BIOS update, but you know how that goes.  Check to see if your motherboard has a new BIOS and if it does, flash it.

Identification

If you are fortunate enough to have a local store that stocks CPU's, the quickest way to identify the new CPU is by the packaging.  Intel's new environmentally friendly packaging is visibly smaller.  However, you should not use this as your sole means of identification.  Some older steppings might have found their way into the new packaging, so you're going to have to look at the label.

Looking at the label is the only way you can be 100% positive that you have a new E0 stepping.  Hopefully, you will have a store with friendly staff that will be patient with you as you ask to look at all of the CPUs they have in stock.  I was fortunate and the guys at SWS really hooked me up.  They only briefly looked at me like I was crazy.  Anyway, you want to look at the S-spec #.  The new E0 steppings are as follows:

If you're out and about and don't have these memorized, just remember the "9".  The older steppings do not have a "9" in them anywhere.