What is the difference betwwen two Xeon CPUs with stepping 11 and 7?

Question

Would you please explain me what kind of differences between these two CPUs have:

1)
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 15
model name      : Intel(R) Xeon(R) CPU           E5345  @ 2.33GHz
stepping        : 11
cpu MHz         : 2324.000
cache size      : 4096 KB
physical id     : 0
siblings        : 4
core id         : 0
cpu cores       : 4
fpu             : yes
fpu_exception   : yes
cpuid level     : 10
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov 
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall lm constant_tsc pn
i monitor ds_cpl vmx est tm2 cx16 xtpr lahf_lm
bogomips        : 4658.31
clflush size    : 64
cache_alignment : 64
address sizes   : 38 bits physical, 48 bits virtual
power management:

---

2)
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 15
model name      : Intel(R) Xeon(R) CPU           E5345  @ 2.33GHz
stepping        : 7
cpu MHz         : 2331.000
cache size      : 4096 KB
physical id     : 0
siblings        : 4
core id         : 0
cpu cores       : 4
fpu             : yes
fpu_exception   : yes
cpuid level     : 10
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov 
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx lm constant_tsc
 pni monitor ds_cpl vmx est tm2 cx16 xtpr lahf_lm
bogomips        : 4658.30
clflush size    : 64
cache_alignment : 64
address sizes   : 36 bits physical, 48 bits virtual
power management:

Please notice only the stepping is different, first one has stepping 11, other 7.

How do I find out how stepping affects the performance between these two CPUs? Does Intel website contain this info?

Regards

Solution

Intel's answer to stepping: http://www.intel.com/support/processors/sb/cs-001665.htm

In short, different steppings are from different manufacturing process and the higher the better.

update:

Having too much free time, I investigated a little deeper. Wikipedia lists the CPU families along with stepping numbers: http://en.wikipedia.org/wiki/Core_%28microarchitecture%29#Steppings_using_65nm_process

E5345 CPUs had two steppings (ever): B3 and G0. Looking at the Wikipedia site, the CPUID of those stepping are:

• B3 - 06F7
• G0 - 06FB

It looks to me that the stepping that is displayed in the CPU info table is actually the last hexadecimal digit (written as decimal) of the CPUID (which refers to the real stepping code).

Comments

[Philip]

The newer stepping model has 2 more bits of physical address width and NX capabilities. It might also use a smaller process, though I'm not sure about that specific model.

[alwbtc]

Thanks, but in the site it talks about stepping with letter and number. With proc/cpuinfo, I get a stepping consisting of only a number. How much is stepping 11 better than stepping 7 for that CPU?

[Nils]

@alwbtc Hex "B" = Decimal "11" Citation from the WiKi: "The G0 and M0 steppings improve idle power consumption in C1E state". 11=G0, 7=B3

[Tch]

That's what I wrote (or I don't get it): G0 -> 06FB -> '11'; B3 -> 06F7 -> '7'