I recently purchased a Compaq Presario v5000z notebook and I am
looking to upgrade the memory on it. I bought it with one 1GB stick of
RAM, which should leave one slot open, which I would like to fill with
another 1GB stick. I *think* I have discovered that the kind of RAM I
need is DDR2 - 533Mhz. This seems to be all I need to know to get
memory that works, but my question is this: besides the qualitity of
the manufacturing, are there any other variables that I should
consider when buying RAM? Are most (well made) DDR2 533Mhz sticks
going to give me the same performance or are there, for example, speed
considerations beyond this. Since I'm going to be limited to a 2GB
system total I want to make every byte count. Thanks!

objectiveblue...

"Are most (well made) DDR2 533Mhz sticks going to give me
 the same performance or are there, for example, speed
 considerations beyond this."

They will give you the same performance. 533Mhz IS the 
speed of the RAM, which is determined, like CPU speed,
by the electromechanical dynamics of the chip, or its
'architecture', and is not subject to change. 

A top name as far as quality goes is Crucial RAM,
though Kingston and EDGE are common choices. Here's
an informative page on RAM from Wikipedia:
http://en.wikipedia.org/wiki/RAM

If you want greater speed, you'd need a faster RAM, if
your motherboard can handle it, as noted on this subpage
of the Wikipedia RAM site:

"DDR2-400: DDR-SDRAM memory chips specified to run at 100 MHz,
 I/O clock at 200 MHz
 DDR2-533: DDR-SDRAM memory chips specified to run at 133 MHz,
 I/O clock at 266 MHz
 DDR2-667: DDR-SDRAM memory chips specified to run at 166 MHz,
 I/O clock at 333 MHz
 DDR2-800: DDR-SDRAM memory chips specified to run at 200 MHz,
 I/O clock at 400 MHz
 DDR2-1066: DDR-SDRAM memory chips specified to run at 266 MHz,
 I/O clock at 533 MHz"
http://en.wikipedia.org/wiki/DDR2

But you can't mix RAM sticks of different speeds, so, if your
motherboard will accommodate RAM faster than DDR2-533, you'll
have to pull the stick you have and try and sell it on eBay,
and replace that with 2 sticks of higher-speed RAM. You can
consult your motherboard user's manual (or download one, if
necessary) to see the RAM it will accommodate.


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sublime1-ga


Additional information may be found from an exploration of
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ram manufacturers
://www.google.com/search?q=ram+manufacturers

A very good answer for the price I paid. More specific information
about my computer would have been nice, but not expected at only $5.

Just a heads up:

From the Compaq website
http://www.shopping.hp.com/webapp/shopping/computer_series.do?storeName=computer_store&category=notebooks/compaq_presario&series_name=V5000Z_series&catLevel=2&tab_switch=true&tab=specs

It does not specifically state the RAM type, it only refers to it as
DDR and it appears it does not list 1GB of RAM in one stick as an
option only 2x512MB.

My suggestion is to download a program called CPU-Z:

http://www.cpuid.com/cpuz.php
Click the link under "Current Version" in the left side

After installing the program and running it, there exists a "SPD" tab:
http://www.maximopc.org/imagenes/reviews/elitegroup-PF88/TEST-INTEL-CPUZ-SPD.jpg

You can view what memory sticks that are installed in your available
slots, their size, type, etc. as well as whether or not a slot is in
fact empty and available for use. It will serve as a guideline for
purchasing more RAM.

Tada.

yes, I found out it was only DDR I, 333Mhz, eventually, which I
suppose is not the fastest, but oh well. I, too, noticed that the 1
stick of 1GB is not an option anymore, but I called to check and it is
indeed what I ordered. Thanks for your help, both of you.