I have searched RAM and i found there are given some specification for the same capacity RAM, What are the difference and performance comparison between these?

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RAM1

General

Brand           Transcend
Memory Type     2 GB (8 x 128 MB) DDR2 DIMM
Memory Standard     DDR2-800/PC-6400
Compatible Device   PC
Pins            240-pin
Burst Length    4, 8
Buffered/Unbuffered Unbuffered

Memory

Memory Clock    400 MHz
Technology      DDR2 SDRAM Memory
CAS Latency     4, 5, 6

RAM 2

General

Brand              Transcend
Memory Type        2 GB (8 x 128 MB) DDR2 DIMM
Memory Standard    DDR2-667/PC2-5300
Compatible Device  PC
Pins               240-pin
Burst Length       4, 8
Buffered/Unbuffered    Unbuffered

Memory

Memory Clock    333 MHz
Technology      DDR2 SDRAM Memory
CAS Latency     3, 4, 5

RAM3

General

Brand           Kingston
Memory Type     2 GB (64 x 256 MB) 800 MHz DDR2 DIMM
Compatible Device   PC
Pins            240-pin
Error Check     Non-ECC
Buffered/Unbuffered  Unbuffered

Memory

Memory Clock    200 MHz
Technology      DDR2 SDRAM Memory
CAS Latency     6

What are the affect of the following

• Memory Type(given as 8 x 128 MB)
• Memory Clock (given in MHz)
• CAS Latency (given as 4,5,6)

my Requirement is 2 GB DDR2 Type Desktop Please help