[ltp] exceeding maximum memory?

[FeRD]

Alex Deucher wrote:

>On 11/8/05, Michael Selway <mas@ssl.co.uk> wrote:
>  
>
>>Hi, I've been happily running linux on a T21 for over 4 years and
>>it's all just fine, except I need more memory 
>>[...]
>>
>>Hmmm - looks like I might be able to put 2 x 512 Mb in there.
>>Does anyone know whether that might work?
>>
>it might work _IF_ you can find 512 MB SO-DIMM that have the right
>size chips on them.  the T20-22 were rather particular about the size
>and speed of the actual chips on the DIMM.  The higher density chips
>don't work.
>
That's a big "if", too, unfortunately -- I'm still seeing 256MB PC133's 
for sale here and there (at twice the price of 512MB DDR266 SODIMMs, 
*grumble*), but I don't think anyone but online specialty companies 
carry anything larger, and then it's hard to get a guarantee that 
they're the right type of DIMM. Plus, unless you have a line on some 
cheap/free memory seconds somewhere, this sort of memory is just 
prohibitively expensive. I've been considering memory upgrades to my T22 
to be a moot point since I've grudgingly admitted to myself that, even 
tho I love the thing, I can get a whole newer-used laptop with more 
memory and better specs for about the same money as I'd end up spending 
to upgrade my T22. Not a justifiable expense, especially since it's a 
dead-end upgrade. (That memory isn't going anywhere with me when I move 
on from the T22.)

...Oh, then there's the fact that on my unit, the right-hinge-area 
case-cracking genetic defect thingy has progressed to the point where 
the whole thing could break in half the day after I drop $300+ on 
memory. (Nevermind that that $300 is pretty much the resale value of the 
whole laptop, these days.) Be like installing satellite radio into a '57 
Ford Fairlane with a cracked engine block.

Going back to Michael Selway's original question: I'd be worried about 
the possibility that dmidecode is making unwarranted assumptions about 
the ThinkPad's available memory configurations. I've had/worked with 
several (desktop) motherboards that, say, had 3 memory slots that each 
supported up to a 512MB DIMM, but couldn't address over 1MB of RAM 
total. You could use 3x256MB SIMMs, or shell out for the big boys and 
only use the first 2 slots. So it's possible that the ThinkPad can take 
512MB in either, but not BOTH, of those slots. Dmidecode probably 
couldn't be aware of that -- so make sure you don't shell out tons of 
money for a 512MB module that ends up making no difference! (Altho you 
could probably not-quite-break-even selling the pair of 256's...)

-FeRD

P.S> Mind you, when I do get a newer machine, this 1400x1050 display is 
gonna make one kickass remote-display client, and 384MB of memory is 
plenty for that.  <EG>