Reading memory markings and designations

Hi All:

I have found one which I cannot answer, and in my search for the truth have ended up with more questions...

I am trying to hunt down compatable system memory.
The MBD uses a serverworks chipset which requires:
PC133 Registered ECC SDram 4 Clock CL3

I have found that on serveral memory sticks by different manufacturers they use a common labeling method

Examples:

PC133R-333-541-A1
PC133R-333-542-A1
PC133R-333-542-B1
PC133R-333-542-Z

Can any one give me a breakdown of what the last two groups represent.

BTW a PC133R-333-542-Z will not peacefully co-exist with a PC133R-333-541-A1 - after a while the ECC is kicking in to resolve memory errors, and the system slows down to about 40%

I went to several MEM websites, most offered basic info - such as the difference between PC100 & PC133 - Also DDR - But they failed to give any help for this question.

Thanks in advance for those who respond!

 

Here's the standard nomenclature from this PDF file:

PC133 SDRAM Unbuffered DIMM Specification


Format:

PC133m-abc-dde-fg

Where:

m: Module Type
R = Registered DIMM
U = Unbuffered DIMM (no registers on DIMM)

a: SDRAM CAS Latency

b: SDRAM minimum tRCD specification (in clocks)

c: SDRAM minimum tRP specification (in clocks)

dd: SDRAM tAC specification (into 50pF load), with no decimal point
54= 5.4ns tAC

e: JEDEC SPD Revision used on this DIMM
2 = JEDEC SPD Revision 2.0

f: Gerber file used for this design (if applicable)
A: Intel® PC100 x8 Based
B: Intel® PC100 x8 Based Low Cost (LC)
C: Intel® PC100 x16 Based
Z: None of the "˜Reference’ designs were used on this assembly

g: Revision number of the reference design used:
1: 1st revision (1st release)
2: 2nd revision (2nd release)
3: 3rd revision (3rd release)
Blank: Not Applicable (used with "˜Z’ above)


Example:

PC133U-333-542-B1 is a PC133 Unbuffered DIMM with CL = 3, tRCD = 3, tRP = 3 and a tAC = 5.4ns, using JEDEC SPD Revision 2 and produced based on the x8 based LC Gerber, 1st release


Further info on the JEDEC SPD:

SPD DATA STANDARDS