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How can I upgrade EDO memory?


I have a 200Mhz Pentium MMX computer with a

vxpro motherboard, with 32mb of SIMM ram installed.

(two 16mb chips). I read on the internet that it

should be able to support up to 256mb of SIMM

modules. The motherboard has 4 simm slots, so I

purchased four 64mb of EDO Simm memory to upgrade it.

My problem, when I boot up, it will not auto detect

any more than 64mb of RAM. I can put in the two

16mb modules with two 64mb modules, and it will

detect 64mb. I can put in only two 64mb modules,

and it will detect 64mb. I can put in four 64mb

modules, and it will still only detect 64mb.

What is the problem?


This question was answered on December 10, 2002. Much of the information contained herein may have changed since posting.

Maddening, isn't it? I've had the same problem with the exact same processor Specifying EDO memory can be a real challenge.

That's sort of an old machine, but probably has a lot of life in it, so don't give up

Since I don't have the exact specs of your motherboard, rather than give you a fish, I'll have to teach you to fish, so to speak You are going to have to do some homework.

First, arrange the modules according to specifications Larger modules, memory-wise need to go into lower numbered sockets, or pairs of sockets.

Find the manual for your motherboard Go through ever scrap of PC literature you have If you can't find it, identify your motherboard You may have to go with the FCC ID number printed on the board Many boards are so generic, that is the only way to identify them Do a Google search on the board, and try to find the manual online

Most manufacturers want nothing to do with end users, so it's amazing how many manuals can be found online There will probably even be a picture of your motherboard.

Read up on the exact memory specs Google any numbers printed on your original memory modules, if need be.

Be sure you are using the same voltage rating of memory, and check for any descepencies concerning parity verses non-parity memory Don't mix 3 volt and five volt memory types They might work for a while, but eventually the outputs of the three volt memory will break down when exposed to five volt outputs from the other modules.

CAS latency is also something you may have to take into account It is a specification in the SDRAM which sets the number of clock cycles between READ commands It sometimes has to be specified in your BIOS settings.

Try this web site for more information:

Where I'm creeping with all this, is that you may have procurred an incorrect type of memory in your newer modules

If none of this brings you any closer to a solution, call one of the memory suppliers with the information you've found and ask if they can supply you with the memory you need You might wind up paying an extra ten dollars for the exact modules you need, but it will be worth it If the modules they ship you won't work, you can send them back.

BTW, you may have to eventually settle for 128 Meg of memory with that machine In my case, the manufacturer's claim that the PC could handle 256 meg was in error However, you'll never notice the difference in performance It's a somewhat slow machine, regardless.


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Posted by Robert of Mesa Community College on December 10, 2002