At 11:15 PM 02/13/2001 Susan Hays wrote:
>
>Is there a lot of difference in performance between having
>128 vs 256MB Ram?  2-128's vs 1-256?


Susan

The previous advice given is correct. If all you do is add another 128MB of
RAM, you may not see any difference. There is, however, a potential
performance advantage in having more RAM. Your management of the greater
memory resources can exploit the difference and appreciably increase
performance. The $50-ish investment in 128MB of RAM is worth it, unless you
have a pokey hard drive or video card and need to upgrade those instead.

If you are willing to play around and tweak your settings, you can make the
PC with 256 MB run faster than a 128 MB system. You have to manually set
various caches in Windows and your applications, perhaps configuring a RAM
drive to cache browsed web pages and copy code (and set paths) to reduce
hard drive I/O. You might run into more complications than the advantage
warrants (it all depends on your hardware and software). There is a
bleeding edge on the learning curve. May not be worth it if, after all the
work and Windows crashes, you only get a 5% boost.

There's a good "In a Nutshell" O'Reilly book called "Optimizing Windows"
that proffers many of the tricks and tips. Magazines and PCBUILD members
post good tips all the time. Everyone has their own little tweaks, though
many seem like voodoo, unless you happen to have that rare combination of
hardware and software that makes the trick "work". Sometimes just thinking
your system is faster makes you work faster so you do gain productivity
(there is no spoon).

Regarding a pair of 128MB DIMMs vs. one 256MB DIMM, some folks recommend
the pair because they believe in spreading eggs into different baskets.
That's risk management. I don't believe DIMMs are interleaved, as were
older SIMMs to enhance performance on some asynchronous memory bus
motherboards (please correct me if erroneous).

The main issue is matching the DIMM pairs. All things being equal (and
assuming well-designed, quality parts), the single 256MB DIMM may
potentially run faster than 2x128MB DIMMs because there may be differences
between the two DIMMs, such as in memory chip type, access time, voltage,
refresh rate (cell leakage), memory skew, heat, circuit design, metals,
etc., which may somehow require the setting of a less than optimal memory
timing for stability's sake. The single DIMM should be internally
consistent while two DIMMs have a potential for less-than-perfect
compatibility (e.g., opposite ends of acceptable parameters).
Well-constructed DIMM circuit boards are as important as the memory chips
mounted on them.

However, SDRAM these days are pretty good, so this is mostly a non-issue
(but try to match your DIMMs anyway). Overclockers' experiences can help
advise you on CMOS memory timing settings, where better and/or matched RAM
allow faster settings. Your mileage may vary....

Hope this helps. Good luck.

John Chin

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