linustalman,

https://www.quora.com/Why-do-32-bit-...ize-3GB-of-RAM

See replies, including:

Check to see if there is a bios update that may address this problem. I couldn't find your specific model on Acer's website but I did see a bios update for the Aspire 5630:

https://www.acer.com/ac/en/US/conten...roduct/539?b=1

Thanks guys. I think I will leave it be at 3GB RAM -- that should suffice.

Have you looked up the correct ram compatibility list...

Same name of ram and even tho 2gb is installed, it may not run as 4gb...

That laptop will run 4gb, just ensure you get the right ram and both chips are correct...

I cant find a compatibility list for acers...

Sorry but it will run with 4gb, just have to sort out why its not...

Check all facets of the ram, ie latency, type, slot type etc etc ... (DDR2 sdram 533 mhz(could run 667mhz))

Hi wraithe.

I think I have 2 other 2*2GB RAM sticks somewhere (not Samsung - not sure of brand) -- I may try them but am not too fussed as 3GB is a big improvement over the old setup of 2GB.

Some thing else to try there, is swap the ram from one slot to the other...

I have had issues with ram being recognized in slot 0 and not in slot 1, yet both chips identical...

The laptop I currently own has been taken from 8gb to 16gb.. Both chips technically identical but different brands.. Put them in and had only 8gb still, yet was recognizing new chip, not old one.. Swap the slots, then it recognized old chip not new... Headache started, so I tried other way around(was considering buying another 8gb chip from same store), then all of a sudden both worked...

Go figure, anyway they test fine, running sweet and ran BOINC for a few weeks to test system(as this laptop hasn't had a work out before) and everything boringly sweet...

Anyway, moral is, not everything makes sense, you just have to try...

PS try one chip at a time, see what develops...

Hello again Pan.

I booted a live distro -- still shows 2.9GB of RAM.

In htop it shows 2.94GB.

Tried all that -- no joy.

If the motherboard has a 32-bit address bus, there's nothing that can be done but to buy a more up-to-date board.

Hi sundialsvcs.

What's the max RAM capacity for a 32-bit address bus? The laptop belongs to a relative and this upping the RAM is more my idea than theirs. They will probably use the laptop until it finally conks out.

4 GB can be handled using 32bit addresses.

The mystery deepens.

What mystery? The cpu iself could use all that ram, but some part of that address space is reserved for another purpose(s). So the hardware, the construction gives a restriction.

I understand, ty.