Member Avatar for Blade10878

Ok, I am gonna try and give as much info on this as possible, I have a Hewlett-Packard Pavilion XE783. I have 64 mb of RAM, and I am attempting to upgrade to 256 mb of RAM. I went to this site Someone from this site recomended it. So i got the correct type of RAM for my computer, I downloaded installation guides, and decided to install myself. I remove the cover look inside and find my current RAM stick in it's slot. Next to it is another slot for RAM, I install the new RAM in the second slot, and left the old RAM in its original slot. I boot back up, and go to see if I had succesfully completed this task, I did not, still reading 64 mb of RAM. My computer is old 1999 I think is when we got it, so I went to get a BIOS update, downloaded instructions and performed that task, then I uninstalled the new RAM, and re-installed it, I still read at 64 mb of RAM, now I don't know what to do, should I remove original RAM stick? Will something like that harm my computer? I am confused and 's tech support is very slow to email me, so I came here, hope someone can help.

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A few simple diagnostics and a little background explain why an older PC often "sees" only one stick even though a second one is seated. As recommended, testing modules individually is the fastest way to separate a bad stick or slot from a compatibility/ordering issue. was also correct to flag module type and the board's limits — those matter a lot on legacy machines.

Try this checklist (safe, deliberate steps):

  • Power down, unplug, and ground yourself before touching the memory.
  • Test each DIMM alone in each slot (stick A in slot 1, then slot 2; stick B the same). Note what the BIOS/POST reports before the OS loads.
  • If a stick works in one slot but not the other, suspect the slot. If a stick fails in every slot, suspect the module.
  • If both sticks work individually but not together, try installing them in the exact slot order recommended by the manual and make sure the retention clips are fully latched.
  • Run a memory tester (Memtest or the motherboard diagnostics) if both sticks are recognized. That helps catch intermittent faults.

Why this happens (plain language):

  • Older boards commonly require matched modules (same size, speed, single/double-sided, and sometimes same manufacturer) to populate multiple banks. Mismatched density or rank can cause the BIOS to ignore the second module.
  • Some systems use paired addressing or interleaving; if modules aren't compatible, only one bank gets enabled.
  • ECC vs non-ECC and voltage differences can also prevent mixed modules from working together.

Practical tips:

  • Consult the motherboard/HP memory spec for supported module types and max per slot before buying replacements.
  • Clean contacts gently and avoid forcing modules. If a module works alone but not paired, the easiest fix is a matched pair or replacing the problematic stick under warranty.

Recommended Answers

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Member Avatar for moderate_rock48

try running the new ram in place of the old ram all by itself and see what happens. HP's can be picky about where you put ram. Change it up and test to see what works.

Member Avatar for Blade10878

Ok I tryed what u said and took out the old RAM completely and put new RAM in old slot, it works! thanks for the advice

Member Avatar for moderate_rock48

you could probably use the 64mb of ram in the other slot.

Member Avatar for sirkeyur

hi buddy...
well there could be multipe reasons why the computer is not able to detect the RAMs. the system might not be compatible wiht the RAM that u have purchased.It could be a SIMM, RIMM or an SRAM or DRAM...there are multiple things that u could have checked before u go ahead and select one.what i would suggest is take the RAM that u have in ur system and then get it checked and get the similar piece. that will solve the purpose.
the other thing is also check out if the motherboard can work wiht 256 MB.

Member Avatar for Blade10878

hi buddy...
well there could be multipe reasons why the computer is not able to detect the RAMs. the system might not be compatible wiht the RAM that u have purchased.It could be a SIMM, RIMM or an SRAM or DRAM...there are multiple things that u could have checked before u go ahead and select one.what i would suggest is take the RAM that u have in ur system and then get it checked and get the similar piece. that will solve the purpose.
the other thing is also check out if the motherboard can work wiht 256 MB.

If you would have read my early post you would have seen were I said I went to , they have a search feature that finds that type of RAM you need with your type of computer.

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