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I'm a bit confused about all the memory types and various bus frequencies of modern consumer PCs. Requesting expert help on the subject.

So far I'm confident that:

  • I have an Asus X51L laptop with an unknown set of configuration options.
  • The CPU in there supports PAE, so I still have a chance to extend the memory beyond 3GiB; and the upper limit of the system is 8GiB. (?)
  • The laptop has two SODIMM slots, one of which is occupied by a 2GiB bank, and the other one is empty.
  • dmidecode and lshw tools consistently state 533 Mhz frequency of the bank.

The last one confuses me the most. I failed to find out characteristics of the northbridge in this laptop, and still can't figure out what DDR2 to seek for. Is it DDR2-1066? Or, rather, PC2-8500/PC2-8600? Wouldn't a DDR2-800 bank harm the system's performance?

Which kind of modules should I look up in stores?

Update: I have bought a 2 GiB DDR2-800 SODIMM, and it seams that the system can't handle 4 GiB of memory. When installed by itself in either slot, both new and old bank (which btw happens to be marked GDDR2-677) work just perfectly; i.e. any configuration resulting in 2 GiB works. When both banks are installed though (totalling in 4 GiB), the memcheck86 tool produces horrible artifacts and crashes, and system reboots; an Ubuntu system can be started and even logged into a Unity session, but the system reboots too in this case from even a minor RAM load.

So it's pretty obvious to me now that this laptop doesn't support 4 GiB of RAM or more.

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migrated from Mar 15 '12 at 21:40

This question came from our site for system and network administrators.

marked as duplicate by Excellll, mdpc, Community Apr 23 '15 at 4:37

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

The best advice I can give you is to download the Crucial Memory Advisor. You don't have to buy your RAM from Crucial (though I would certainly recommend them), but this tool will tell you exactly what kind of RAM you should be buying, and what your best upgrade options are.

Also if you DO purchase your RAM through Crucial using their memory advisor tool and it doesn't work I believe they still give you a full refund.

On the off-chance you're running Linux/BSD/something where the Crucial tool isn't an option, you can use dmidecode (if installed) to get similar information. It will provide you output like this:

Memory Device
    Array Handle: 0x0028
    Error Information Handle: Not Provided
    Total Width: 72 bits
    Data Width: 64 bits
    Size: 1024 MB
    Form Factor: DIMM
    Set: None
    Locator: DIMM0
    Bank Locator: BANK0
    Type: Other
    Type Detail: Other
    Speed: 1333 MHz
    Manufacturer: Manufacturer00
    Serial Number: 00000000
    Asset Tag: AssetTagNum0
    Part Number:                   
    Rank: Unknown

Which you can then match up to memory specs from manufacturers/retailers.

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Unfortunately they don't seem to have a Linux version of the tool, so this doesn't quite solve the problem for me. I'll try to use their on-site support materials though. – ulidtko Mar 15 '12 at 21:47
@ulidtko Specifying your OS in the tags often gets you better (OS-Specific) advice :-) – voretaq7 Mar 15 '12 at 21:53
@voteraq7, well, this is pretty much a hardware question... – ulidtko Mar 15 '12 at 21:57
update: yes, I've used dmidecode tool, it shows me DDR2 memory bank with a line Speed: 533 MHz (1.9 ns). Does that mean that I should go for DDR2-1066? It's barely available in the stores. – ulidtko Mar 15 '12 at 22:16
Hmm, that does seem to say you have a 2GB module and an empty slot. Are you 100% sure it's an X51L? – David Schwartz Mar 16 '12 at 0:57

Upgrading your laptop should start with the RAM module and the processor itself, although it's more likely for a user to change the RAM module for a better one rather than the core of the gadget.

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