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memory not recognized

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by jimuccello

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dell latitude cpx h500
Only 128mb of ram being recognized. 256mb installed. Any ideas?

8 replies

by thechas

There are several possibilities here.

First, does BIOS see all of the RAM?
If so, then you may have 128 MB dedicated to video.

If the BIOS only sees 128 MB, then you most likely have an incompatible RAM module.

Not all SDRAM is the same and many systems are rather finicky about what RAM will function. See if you can find RAM that is specific to this model.

Chas

by jardinier

Hi Chas

I don't know one type of RAM from another. Does the term "double-sided" mean anything to you? I understand that if the wrong memory stick is inserted in an incompatible memory slot it will read as only half it's capacity.

I recently had a computer upgraded. It had two memory slots with a 64 MB stick in each making 128 MB. However the machine could not read two 256 MB sticks, so we ended up with one 256 and keeping one of the 64, making 320 MB altogether.

I am not sure but I don't think we tried using a single 512 stick because of the cost.

by thechas

Hi Julian,

At one time, it was easy to recommend finding a double sided DIMM to take care of issues.

I have lost track of just how many different restrictions I have come across on motherboards that use 168 pin DIMM Memory.

Of course, part of this is a testament to just how old the 168 pin DIMM is. The first ones were used on 486 systems. Depending on how you count your computer history, that is at least 7 generations back from current technology.

The sad thing is that many of the designers and manufactures were not sure what the actual limits of their motherboards were as they designed toward a specification for hardware that did not exist to try.

Only when the new larger capacity or higher density memory chips came to market did they find out if the theory worked.

For those who have been involved with computers long enough, these issues are not new. We had similar problems with the old 30 and 72 pin SIMM modules.

My brother had a 486 system that had 8 30 pin SIMM sockets and 2 72 pin SIMM sockets where you used jumpers to configure the RAM. Talk about set-up issues!

Anyhow, the lower the density of the memory technology, the more compatible the DIMM will be.

Chas

by jdclyde

First, is this the original memory?

Was it recognized at one time?

Did you just add to it?

Did you check (like TheChaz said) if the other 128 is being leached by your on-board video?

What are the specs of the Ram?

Is it one chip?

Try it in another system?

by mayhem1969

As TheChas and jdclyde intimated, is this added memory or something that just started happening? You could swap the nonregistering memory stick with the memory stick that is registering and boot up (one stick in). If it doesn't boot up or register you most likely have a bad memory stick. If it boots up and registers, its not the memory. Put the other stick into the other slot (both sticks in) and boot it up again. If it registers fine, if not, it's sounds like a problem with the memory channel.

by jdclyde

if you put ANY stick in the third slot, it would crash.

choices were, change motherboard or don't use that slot. I didn't use the slot.

by jardinier

Hi Chas

I think the first computers I worked with only had 30 pin memory. Many of those machines were very picky about which memory sticks they liked.

Then I moved on to machines which used 72 pin memory. I found these even more fussy about compatible RAM.

HOWEVER it was with great amazement and delight that I found a Macintosh LC II actually was quite happy with the 4 MB 30 pin memory stick I added to it, which had originally come from a Windows PC.

I have abandonded playing with computers now but I have found the newer memory -- 168 pin -- seems easier to match with the motherboard than the earlier, smaller memory.

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