# Can linux detect ram larger than bios is able to?

## nasaiya

This might be a stupid question but I have to ask...

I have a 1 gig ram stick that for some reason one of my old pentium 4 boxes won't detect properly. Supposedly this motherboard/bios is capable of using a 1 gig stick, yet it only reports as somewhere around 512mb. Is it possible to ignore what the bios says about it altogether in linux and use the kernel etc to detect the actual size? Or is this impossible because if the bios can't detect it, linux can't either...?

Thanks!

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## aceFruchtsaft

I don't think this is only a BIOS limitation, but is determined by the chipset specs. So the answer is no, and that's why you better check the motherboard manufacture's hardware compatibility list before buying RAM.  :Wink: 

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## ksp7498

Indeed, this is a chipset limitation.  It's likely that this is a high-density vs. low-densisty memory issue.  Remember that each stick of ram is really two "banks" of ram put together.  When the mobo says that it can address 1GB sticks, it probably means 512MB per bank.  If you have a high-density 1GB stick (meaning it has 1GB on 1 bank and nothing on the other) instead of a low-density stick (512MB on both banks) then it will only see half of the total capacity.  Look at the stick itself; are all of the memory chips on one side of the stick?  If so, then that's what's going on here.

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## nasaiya

Thanks for the replies... learn something new every day. Anyway it does actually have the memory chips on both sides. I'm not sure what that means as far as my problem though. It's possible the board just doesn't like this particular ram stick. I can't say with any certainty that the two are compatible although it's the only motherboard I have that will even turn on with that stick installed.

I actually bought it for a different computer a couple years ago (before I was smart enough to check compatibility  :Wink:  so I'm basically trying to see if I can put that wasted money to some use here in this old box. It's an MSI motherboard so I found their support website and sent them a ticket asking them the same question so I'm hoping they can help me figure this out as well but I'm not counting on it.

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## energyman76b

 *ksp7498 wrote:*   

> Look at the stick itself; are all of the memory chips on one side of the stick?  If so, then that's what's going on here.

 

and that is wrong.

The placement of the memory chips on the stick has nothing to do with its logical distribution.

There are one sided 'two bank' sticks, and two sided 'one bank' ones. The only way to find the real answer:

manufacture docs. Read the specs for the stick.

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