need education about memory specs....

[silicon]

What is the difference between these specs besides having different numbers...?
F3-10666-CL9-9-9-24 and F3-12800-CL10-10-10-10-30

 

[LTC8K6]

https://en.wikipedia.org/wiki/DDR3_SDRAM

That pretty much explains it all.

 

[myocardia]

The difference is that these sticks here are considerably faster than both of those: http://www.newegg.com/Product/Product.aspx?Item=N82E16820148657

 

[mfenn]

What is the difference between these specs besides having different numbers...?
F3-10666-CL9-9-9-24 and F3-12800-CL10-10-10-10-30

Those look like G.Skill product numbers, but the general idea is the same for all RAM. To break down the fields:

F3 = DDR3
10666 = Peak data rate in MB/s, directly proportional to clock speed. 10666 is DDR3 1333 MHz, 12800 is DDR3 1600 MHz
CL9 = 9 cycles of CAS latency, this is the number of cycles between sending a command to the memory and when it begins to reply
9 = 9 cycles tRCD (RAS to CAS delay), this is the number of cycles between activating the memory line and activating the memory column
9 = 9 cycles tRP (RAS precharge), the number of cycles between disabling one memory line and enabling another
24 = 24 cycles tRAS (Active to precharge delay), the number of cycles between accesses to memory

The broad strokes are that the higher the frequency the better, and the lower the timings the better. Keep in mind that the timings are given in terms of cycles, so the same timings at a higher frequency are faster in absolute terms. For example:

At 1333 MHz, one cycle takes 0.75 ns, so a CAS latency of 9 represents 6.75 ns of real time.
At 1600 MHz, one cycle takes 0.625 ns, so a CAS latency of 9 represents 5.625 ns of real time.
At 1600 MHz, a CAS latency of 10 represents 6.25 ns of real time.

So in the modules above, the DDR3 1600 kit is all around faster even though the timings appear to be looser.