[sf-lug] Adding memory to a computer

[Rick Moen]

Quoting John Strazzarino (jstrazza at yahoo.com):

> I have a dell optiplex cpu and needed to add memory.  I checked the
> memory against dell website and got the identical memory from eBay.  I
> put it in the computer and it just beeps three times.  I’m guessing I
> either got bad memory or some part of the specs I missed.
> 
> Any ideas?

1.  First and foremost, baseline the state of the system:  Unplug the
Dell from the wall.  Yank out the new RAM sticks, and put back the old
ones.  Warning:  Not all RAM sockets are equal.  Make sure you put the
original RAM into the same set of sockets they were in before.  Check
seating of the RAM, carefully.  (Needless to say, in all of this, you
need to be careful about static electricity discharge.)  Plug the Dell 
back into the wall.  Power it up.  Does prior normal operation resume?
If so, you have re-validated your starting point.  If not, then your 
problem becomes 'OK, what has changed since I powered down the first
time?'  

2.  If you still hear the beeps, look up what they're alleged to
indicate.  (Tip of the hat to Ken, on this point.  Good work!)
Investigate and, with luck, fix whatever that problem is.

3.  Assuming you revalidated the baseline, then start again.  Unplug 
the Dell from the wall.  Carefully add the new RAM sticks.  And, by the
way, did you heed system documentation about where RAM sticks must be
placed?  Sometimes, they must be added in matched pairs, and only to
specific sockets.  The sockets are typically labelled '0', '1', '2', '3',
or something like that.  (Gently) make very sure all sticks are firmly 
and un-crookedly in their sockets.  Power up again.  

4.  Problem persists?  If so, you could, to gather information, do
another test bootup with only the _new_ sticks in place and the old ones
_removed_.  This assumes that the motherboard is spec'd to be able to
start from the new RAM size you bought.

Some motherboards dislike particular combinations of RAM sizes (but you
said 'identical memory', so I hope that means same size and speed).


This won't help you at the moment, but, as a general observation:  If
the budget permits, it's almost always wisest to buy, as new RAM sticks,
the densest stick size (megs/gigs per stick) that the motherboard is
known to be able to use.  This is true even if (and maybe especially if) 
your motherboard has only two RAM sockets, and each currently has a
low-density stick (like 256Mb) in it.  Your best bang for the buck will 
pretty much always be to replace the two low-density sticks entirely
with a new pair that's the highest density the motherboard is able to
use.

Exceptions would be border cases like an IA32 (32-bit) motherboard known
to be incapable of addressing any RAM over 2.5 GB.  Even if the
motherboard docs say 'Sure, you can use a pair of 8GB sticks', that
would be a waste of money given the documented memory-space limit.

Also, think carefully before sinking $100 for RAM replacement into an
old motherboard (like, pre-2015).  Your performance improvement from 
that will not be worth the money, compared to getting a newer box, and 
old computers are pretty reliably bottlenecked in _lots_ of areas at the
same time, e.g., slow CPU, slow RAM, slow hard drive.  Throwing money at 
_one_ of those areas won't help a lot, and you should save your money.
(OTOH, if you happened to have compatible extra sticks of RAM sitting in
a drawer unused, why not?  Opportunity cost, then, is about zero.)