2gb Ram showing as 1.5gb

thinkjim used Ask the Experts™

I have an HP Microtower  (HP DC5100M,P4-530). I've installed 2x 1gb DDR2 533mhz chips in the machine and the bios is only showing 1.536gb of RAM.

Each RAM module will show as 1gb in the bios if installed alone, but will only show up as 1.5gb if installed together. I have tried installing the RAM in slots 1&2 (shows as single channel) and then in 1&3 which shows as (asynchronous) in the bios.

I know I've come across this before, but I can't remember what the cause is. Is it because the motherboard needs a matched pair? I have 3 slots.

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That amount of Ram is used by your onboard graphic card, i guess. You can enter Bios to reduce memory shared for onboard Graphic
Graphic Card should only use 128MB if you see the specs.


See "Memory" for detailed informations about how to install your memory correctly.
Does your Mainboard really have 3 Memory Slots or what do you mean with "I have 3 slots"?
Sorry i did not read carefully. Try entering bios to find "Memory mapping" option and enable it.
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No need to worry in this because display way sharing the memmory. or u may allocate the memmory for paging file.

Kindly check both of them.

Please check that your motherboard supports 2 gb ram.

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