Cam anyone help me answer that question? I have a compaq Presario using PC2700 512gb DDR-333 184 pin ram. I am told I have 2 slots. Will the machine be faster with two 512's or one 1024??

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Last Post by Kegtapper

The speed of the RAM depends on the "MHz" reading after some numbers. The bigger that number the better. You should always install RAM in matching pairs for best results. Please use this site:
Crucial will tell you what type of RAM your system currently uses, and the clock speed, "xxxMHz" (xxx being any set of numbers). The bigger the number the faster the RAM will be at processing data. The size (512Mb, 1024Mb/1Gb) is just the capacity of the RAM stick.


If your motherboard supports dual channel memory, then 2 x 512 would be faster. They must be a matched pair for dual channel.

If your motherboard does not support dual channel memory, a single 1GB module would be slightly faster.

Memory speed is limited by FSB speed. Faster memory won't matter unless supported by FSB speed. It'll work, just at slower speed.


I think it is very important that you not overlook a third possibility, which I think would be by far your best choice: 2 x 1024.

If you intend to run Vista, you need 1 GB just to support Vista. 2 GB of RAM is nothing at all excessive—it is merely the recommended RAM in today's notebooks.

I would urge you to follow all the advice you've been given above, but change the numbers so you are installing your maximum RAM capacity into your machine—which is likely 2 GB total.


i think 2*512mb would be best if u have dual channel ram. even if u don't, your mobo would "see" more ram (2 is bigger than one), and therefore slightly improve performance. having two ram chips will also improve failure levels (if one stick fails, u still have 512mb left!!)

as Groox said, consider adding 2*1024 or even 2*2048 (if options exist to do so for your configuration). Ram isn't that expensive, but is a major speed criteria. If you want to run vista, it will eat lots of ram, and the more u add, the better ur vista situation. if sticking with xp or below, 1gb should be more than enough.


Wow- where are you techs graduating from?

There is no speed difference between the two. RAM is RAM, when Blocked it is blocked into contiguous space.

But there are factors to consider with that model.
1: is it capable of using 1GB DIMMS
2: Will you need more later?

If you fill both of them with 512mb and down the road, you upgrade to Windows Neutrino (or whatever is after VISTA) you will be back to square 1- trying to find memory for an ancient machine.

I would suggest getting 1GB stick now, and have a slot available for 'future'. And that suggestion depends on your budget.

Their is no speed advantage, a program address jump to a farther memory location will be the same distance and time.


In single channel mode, one larger stick will provide slightly better performance than two smaller sticks because the memory controller only has to address one slot. The difference is extremely small, but real.

I'd suggest someone study up on memory controllers.


Will -
It is a Compaq Persario using DDR (double data rate).

Not using Dual Channel, RAMBUS or other 'exotic' flavors. and still will only achieve 2700mbps. There are no synchronus/asynchronus modes for that model, if there were, the sockets would have come filled, and would be listed as Channel A/B rather than DIMM1/2.

Even the higher end r3000 & r4000 didn't use Dual Channel.

Been studying, and have studied over 20 years as well as designing and moding


What does that have to do with one vs two modules in single channel?

I didn't start repairing PCs last week either. May just have more experience than you.

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