Wednesday, May 23, 2001
Identifying DIMM Module by Label
JEDEC has also issued a standard for labeling the DDR DIMM module. A standard DDR DIMM module should have at least one label on the module. The label should contain the following information:
wwww = Module Bandwidth
1600: 1.6GB/sec or 2100: 2.1GB/sec.
m = Module Type
R= Registered DIMM
U= Unbuffered DIMM (no register on DIMM)
aa = SDRAM CAS Latency, with no decimal point (25=2.5ns CAS Latency)
b = SDRAM minimum tRCD specification (in clocks)
c = SDRAM minimum tRP specification (in clocks)
d = JEDEC SPD Revision used on this DIMM
e = Gerber file used for this design (if applicable)
A= Reference design of R/C A is used for this assembly
B= Reference design of R/C B is used for this assembly
C= Reference design of R/C C is used for this assembly
D= Reference design of R/C D is used for this assembly
E= Reference design of R/C E is used for this assembly
F= Reference design of R/C F is used for this assembly
H= Reference design of R/C H is used for this assembly
K= Reference design of R/C K is used for this assembly
Z= Reference design of R/C Z is used for this assembly
f = Revision number of the reference design used:
1 = 1st revision ( 1st release)
2 = 2nd revision (2nd release)
3 = 3rd revision (3rd release)
Bank= Not Applicable (used with Z above)
Is a PC1600 DDR Registered DIMM with CL=2.5, tRCD=3, tRP=3
Using the latest JEDEC SPD Revision 0.0 and produced based on the A raw card Gerber, 1st release.
A Note on Module Bandwidth
In theory, higher memory bandwidth will deliver better performance for the computer system. Memory peak bandwidth is defined as memory bus width/8 bits x data rate.
That translates into how fast your 3D games will react, how smooth your MP3 music will play or how good a motion picture you can play in your MPEG video streaming. Bandwidth calculation: memory bus width/8 bits x data rate.
For example: memory bus width for the 184pin DDR module is 64bits, data rate of the DDR SDRAM is usually 266MHz. That makes the peak bandwidth = 64/8X266MHz = 2100MHz.
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