If I recall correcly, tried looking but couldn't find it immediatly by googling, the compaq armada series uses an intel 440BX chipset.
That chipset has a limitation on the maximum size (bits) of each memory chip supported.
Not all such modules will work.
memory modules with 4 or 8 chips for the 256MB will not work due to this limitation.
only a module with 16 chips will.

that is, If it's the 440BX chipset which I recall. If the chipset is different, the limitations could be different.

This is one I bought for an armada m700
https://ram-co-shop.de/256-MB-SO-DIMM-144-pin … ip-double-sided

Unfortunately it is out of stock in that shop.

weedeewee wrote on 2023-06-15, 12:17:

If I recall correcly, tried looking but couldn't find it immediatly by googling, the compaq armada series uses an intel 440BX ch […]
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If I recall correcly, tried looking but couldn't find it immediatly by googling, the compaq armada series uses an intel 440BX chipset.
That chipset has a limitation on the maximum size (bits) of each memory chip supported.
Not all such modules will work.
memory modules with 4 or 8 chips for the 256MB will not work due to this limitation.
only a module with 16 chips will.

that is, If it's the 440BX chipset which I recall. If the chipset is different, the limitations could be different.

This is one I bought for an armada m700
https://ram-co-shop.de/256-MB-SO-DIMM-144-pin … ip-double-sided

Unfortunately it is out of stock in that shop.

I ordered this one with this lable on it

256MB PC133S-333 CL3
SDRAM 133MHz 144-PIN 3.3V SODIMM

i dont know if it will work!

googling that gives a module with 8 chips.
Best case, it works.
Worst case it doesn't.
Likely case, it only works at half capacity.

did it have EDO or SDR ? in theory even a 440BX should support loads more , at lest 128+256.... depending on a bios of corse E500 isn't that a P3? I use to work with them.... I may even have one somewhere to test ram... hmmm https://www.memorystock.com/memory/CompaqArmadaE500.html and https://www.compuram.biz/memory/hp-hpe/notebo … da/series/e500/ - that you are ok up to 512.... even manual says so.

ediflorianUS wrote on 2023-06-16, 08:54:

did it have EDO or SDR ? in theory even a 440BX should support loads more , at lest 128+256.... depending on a bios of corse E500 isn't that a P3? I use to work with them.... I may even have one somewhere to test ram... hmmm https://www.memorystock.com/memory/CompaqArmadaE500.html and https://www.compuram.biz/memory/hp-hpe/notebo … da/series/e500/ - that you are ok up to 512.... even manual says so.

you're confusing the issue. the e500 only has 2 so-dimm slots, so a max of 512M ram is correct and the 440BX supports a max of 1GB
BUT ! and here is the catch.
The 256M so-dimm modules must be composed of the correct amount of chips for that setup to work.
Newer modules with less and newer higher capacity chips do not work fully or at all. at best you get a reduced capacity of available memory.