Can 64 MB SIMM look like 16 MB SIMM

[PracticalProgram]

Recently purchased four, 64 MB SIMMs (72-pin) for an old computer, for a total of 256 MB.

Installed the SIMMs, all four at a time, two at a time (in one bank, then another bank), etc., etc. I tried all combinations. Each time, the SIMMs calculated out to be 16 MB apiece, for a total of 64 MB.

Sellor had me confirm that the motherboard can recognize the memory, and it can (at least according to the literature that came with the motherboard). In fact, I currently have four 32 MB SIMMs installed, for 128 MB of memory.

I bought the memory to a third party who, with a memory testing machine, determined that the SIMMs are 16 MB apiece.

Sellor has stated that memory can sometimes appear smaller than it is. In other words, the sellor is saying that some motherboards will recognize only 16 MB of a 64 MB SIMM.

I've talked to several people who have said that a motherboard may not recognize whole SIMMs above a certain memory limit, but that it will never "see" a SIMM for something other than what it is.

Can you people shed some light on this? Is a SIMM, if recognized, ever recognized at other than it's rated value?

Thanks for help.

 

[Kingofcomputer]

you should check your motherboard's manual first.
it could be your motherboard's chipset doesn't support 64MB SIMM or doesn't support the ram chips (organization, density) on this module.

 

[PracticalProgram]

Thanks Kingofcomputer. I've checked my motherboard manual and it accepts several dozen combinations of SIMMs, including a number of combinations using 64 MB SIMMs, even a single, 256 MB SIMM. The motherboard is limited, however, to 256 MB total.

As for the motherboard chip set, if this helps, it is an Intel 82439HX chipset, with an Intel 82430HX system controller and an AMI BIOS.

You mentioned that it is possible that the motherboard will not recognise a particular arrangement of chips. Is there a way to determine, from the chip numbers, what the SIMMs are?

There are four chips on each side of each SIMM, for a total of eight chips per SIMM board. Each chip has the following number on it:

USA
40016LD5DW-SS

Can one determine the size of the SIMM from this information?

Thanks.

 

[LukFilm]

http://www.memoryx.net/tr72e64.html

 

[zephyrprime]

I've had this happen before. If a computer only supports 16mb simms and you stick a bigger simm into it, it will think it's a 16mb simm. But in your case, I don't think this is the problem because:
1. your manual already states that it can support 64mb simms
2. your mb has already demonstrated the ability to support 32mb simms so it should at least think the 64mb simms are 32mb.
3. your friend's simm tester thinks the simms are 16mb.

The seller is just reluctant to accept the mechandise back because he knows he'll never have another chance to unload such an obsolete memory product.

You can also simply calculate the size of memory if you know how to read the numbers on memory chips. For example, I have 2 sodimms on my desk right now. One is 32MB and the other is 512MB. On the 32MB sodimm, each chip has a product number that ends in "vct8pc". The 8 means 8MB. The sodimm has 4 chips. 8MB*4chips = 32MB which is as expected.

On the 512MB sodimm, the chips part number ends in "32LLCTW". The sodimm has 16 chips. 32MB*16 = 512MB as expected.

My examples were with sodimms but the information is generally applicable to all sorts of ram because ram chips always have their size written on them.

Just print this out and show it to your merchant if you have to.

 

[Kingofcomputer]

Intel 430HX chipset spec:
http://www.intel.com/design/chipsets/datashts/290551.htm