Dumb memory question

[Mike Shepherd]

This will probably sound like a dumb question to computer
literate people, but here goes.
I`m planning to add memory to a system. I know it`s best to
add memory dimms in pairs and that all dimms existing and
added should be the same speed. In this case DDR2 800.

But while looking at memory dimms I noticed that some
run at 1.8 volts, 2.0 volts, 2.1 volts, ect.
Does it matter if this is mismatched with the dimms I
already have installed in the system?

Also noticed that different "Timing" is listed in memory
for sale. I have little understanding of this, but assume
that lower is better.
Does it matter if the Timing is mismatched with the memory
I already have in the system?

 

[Dave]

This will probably sound like a dumb question to computer
literate people, but here goes.
I`m planning to add memory to a system. I know it`s best to
add memory dimms in pairs (SNIP)

No it's not. That's a common misconception, though. Some mainboards can
run RAM in dual channel mode, using two (fairly matched or perfectly
matched) sticks of RAM as one. This improves RAM performance slightly, but
doesn't have a significant impact on overall system performance. So it's
not "best" to add memory dimms in pairs. In general, it's good to LIMIT the
total number of sticks of RAM installed, as systems can become unstable with
too many physical memory boards installed.

and that all dimms existing and
added should be the same speed. In this case DDR2 800.

That we can generally agree on. It is over-simplified a bit, but
essentially correct.

But while looking at memory dimms I noticed that some
run at 1.8 volts, 2.0 volts, 2.1 volts, ect.

Well they don't run at 1.8 volts or 2.0 or 2.1 really, but that's what they
are rated at. This is tough to explain, but it boils down to, lower timings
acheived at lower voltage is a good thing. If two sticks of ram are
identical but one is rated at 1.8 rather than 2.0, then the 1.8v rating ram
is likely of higher quality. But this only matters if your mainboard is
really REALLY picky. That is, some mainboards only run stable with really
high quality ram, so you will see people suggest using 1.8 ram for those
particular mainboards.

Does it matter if this is mismatched with the dimms I
already have installed in the system?

Probably not, unless you own one of the really picky mainboards, or are
planning to overclock the heck out of your system.

Also noticed that different "Timing" is listed in memory
for sale. I have little understanding of this, but assume
that lower is better.

That is correct. CAS3 is better than CAS4 for example. In real-world use
though, the proper amount (capacity) of RAM is more important to performance
than CAS ratings. A system starved for ram will be a real dog whether the
ram is CAS4 or CAS2! But with enough RAM (capacity) installed, you won't
notice a significant difference in system performance by upgrading from (for
example) CAS4 to CAS2.

Does it matter if the Timing is mismatched with the memory
I already have in the system?

Yes and no. Your mainboard should be able to run mismatched RAM just fine,
as long as EVERY individual stick of RAM is actually supported by the
mainboard. The problem is, to keep the system stable, the system will
likely have to slow down all RAM to the speed of the "slowest" RAM you have
installed. In some extreme cases, you might have to tweak the BIOS settings
manually to force the mainboard to slow down.

I'll make this simple for you. You mentioned DDR2 800. Take a look at what
you currently own, and aim for total capacity of 1.5GB to 2.0GB of RAM with
as few sticks of good name-brand DDR2 800 RAM as possible. For example, if
you have two sticks of 512MB currently, add just one stick of 1GB, for a
total of 2GB. If system becomes unstable, try removing one of the 512MB
sticks and try again.

For name brand, look at Kingston or OCZ, just to mention a couple of good
ones. Corsair, Crucial and Mushkin are all good as well. I'd suggest you
try Kingston, as this brand seems to have few compatibility problems and is
generally pretty good quality without being very expensive. For a more
specific recommendation, if you are sure that your mainboard needs DDR2 800,
try the following as an upgrade. Buy just ONE. No need to add two of them.
Yes, there are some slightly cheaper sticks of RAM on newegg I could
recommend, but this one is rated at 1.8v, and has a heat spreader (I
personally like heat spreaders, personal preference...not necessary really
but it can't hurt!) -Dave

http://www.newegg.com/Product/Product.aspx?Item=N82E16820146117

 

[Jan Alter]

No it's not. That's a common misconception, though. Some mainboards can
run RAM in dual channel mode, using two (fairly matched or perfectly
matched) sticks of RAM as one. This improves RAM performance slightly,
but doesn't have a significant impact on overall system performance. So
it's not "best" to add memory dimms in pairs. In general, it's good to
LIMIT the total number of sticks of RAM installed, as systems can become
unstable with too many physical memory boards installed.



That we can generally agree on. It is over-simplified a bit, but
essentially correct.



Well they don't run at 1.8 volts or 2.0 or 2.1 really, but that's what
they are rated at. This is tough to explain, but it boils down to, lower
timings acheived at lower voltage is a good thing. If two sticks of ram
are identical but one is rated at 1.8 rather than 2.0, then the 1.8v
rating ram is likely of higher quality. But this only matters if your
mainboard is really REALLY picky. That is, some mainboards only run
stable with really high quality ram, so you will see people suggest using
1.8 ram for those particular mainboards.


Probably not, unless you own one of the really picky mainboards, or are
planning to overclock the heck out of your system.


That is correct. CAS3 is better than CAS4 for example. In real-world use
though, the proper amount (capacity) of RAM is more important to
performance than CAS ratings. A system starved for ram will be a real dog
whether the ram is CAS4 or CAS2! But with enough RAM (capacity)
installed, you won't notice a significant difference in system performance
by upgrading from (for example) CAS4 to CAS2.



Yes and no. Your mainboard should be able to run mismatched RAM just
fine, as long as EVERY individual stick of RAM is actually supported by
the mainboard. The problem is, to keep the system stable, the system will
likely have to slow down all RAM to the speed of the "slowest" RAM you
have installed. In some extreme cases, you might have to tweak the BIOS
settings manually to force the mainboard to slow down.

I'll make this simple for you. You mentioned DDR2 800. Take a look at
what you currently own, and aim for total capacity of 1.5GB to 2.0GB of
RAM with as few sticks of good name-brand DDR2 800 RAM as possible. For
example, if you have two sticks of 512MB currently, add just one stick of
1GB, for a total of 2GB. If system becomes unstable, try removing one of
the 512MB sticks and try again.

For name brand, look at Kingston or OCZ, just to mention a couple of good
ones. Corsair, Crucial and Mushkin are all good as well. I'd suggest
you try Kingston, as this brand seems to have few compatibility problems
and is generally pretty good quality without being very expensive. For a
more specific recommendation, if you are sure that your mainboard needs
DDR2 800, try the following as an upgrade. Buy just ONE. No need to add
two of them. Yes, there are some slightly cheaper sticks of RAM on newegg
I could recommend, but this one is rated at 1.8v, and has a heat spreader
(I personally like heat spreaders, personal preference...not necessary
really but it can't hurt!) -Dave

http://www.newegg.com/Product/Product.aspx?Item=N82E16820146117

Thanks Dave. I can glean something from your explanation as well and very
much appreciate the details described in a clear manner, without sarcasm or
a demeaning delivery. Mike's question is intelligent rather than "dumb".

 

[Dave]

a demeaning delivery. Mike's question is intelligent rather than "dumb".

That's what I was thinking. Better to ask about memory before buying than
to buy the wrong memory and THEN ask what's wrong with my system now?
-Dave

 

[Mike Shepherd]

"

That's what I was thinking. Better to ask about memory before buying than
to buy the wrong memory and THEN ask what's wrong with my system now?
) -Dave

Thanks for the info.
And I`m not really surprised that some of what I "thought" I knew wasn`t
really
accurate.
I see this all the time in areas where I do know what I`m doing.
In my free time I`m a part time firearms instructor. Every once in a while I
see people
(including cops and ex military) that are absolutely sure they know
something
because someone once told them.....they once read somewhere..... or even
because they once saw a hollywood moron do something incredibly stupid
in a movie.

I always figured that if you are not sure what you are doing, it can`t hurt
to ask someone
who does.

Thanks again for the information.

 

[philo]

"

Thanks for the info.
And I`m not really surprised that some of what I "thought" I knew wasn`t
really
accurate.
I see this all the time in areas where I do know what I`m doing.
In my free time I`m a part time firearms instructor. Every once in a while I
see people
(including cops and ex military) that are absolutely sure they know
something
because someone once told them.....they once read somewhere..... or even
because they once saw a hollywood moron do something incredibly stupid
in a movie.

I always figured that if you are not sure what you are doing, it can`t hurt
to ask someone
who does.

Thanks again for the information.

The only "dumb" question is the question unasked.

BTW: There *is* such thing as a dumb answer however .<G>
(not on this thread though)