extra RAM - silly question

Marty_J

Domokun wrote: »

There's no way that a pair of new 1gB sticks balanced across the ports will perform better than adding the existing two 512 mB sticks as well? I know it sounds odd...

I'm not sure I understand what you're asking. How many RAM slots do you have?

Marty_J

Belnahua wrote: »

If it only had 3 slots to start with, then it's not using matched pairs!

It would need a multiple of 2 slots to suggest it uses matched pairs!

The OP is the one with 3 RAM slots.

I'm not sure how many Domokun has.

Domokun

4 ports, dual core. Two A and two B ports, they'll need to be balanced as you say. If I can get a hold of a 'benchmarking' test program I can answer my own question.

Marty_J

Well in that case, put the two 1 GB sticks in the A ports, and your old 512 GB sticks in your B ports. As I said before, having an extra GB will make much more of a difference than only using matched RAM.

fwor

Domokun wrote: »

I'm in a similar position with a dual core, which is what I think you were trying to put across about matching pairs. You mention a 'benchmark' test for comparing RAM setups. I'm looking to buy 2x1GB sticks for my PC, and I'd love to have a test to see whether I'd be better off keeping the existing two 512 sticks in, or binning them in favour of just the 2 1GB sticks.

Did you have a specific program in mind when suggesting a benchmark test?

Whether you'll get better performance by removing the older memory will depend largely on whether it has worse timing (in terms of CAS latency, etc.)

You can use PCWizard to examine the DRAM timing of all of the modules in the PC, and it also has benchmark programs built in:

http://www.cpuid.com/pcwizard.php

weegie.geek

Domokun wrote: »

4 ports, dual core. Two A and two B ports, they'll need to be balanced as you say. If I can get a hold of a 'benchmarking' test program I can answer my own question.

Can people stop saying they NEED to be in pairs? Not since RIMMS running dual or quad channel have you *needed* to pair ram.

You can quite happily have a 256MB, a 512MB and a 1024MB stick in a DDR/DDR2 system. The ram won't run in dual channel mode (nothing whatsoever to do with dual core processors) but since dual channel ram gives such a tiny performance boost it's usually better to go for the extra ram and stay single channel than to go dual channel and have less ram.

marms

weegie.geek wrote: »

Can people stop saying they NEED to be in pairs? Not since RIMMS running dual or quad channel have you *needed* to pair ram.

You can quite happily have a 256MB, a 512MB and a 1024MB stick in a DDR/DDR2 system. The ram won't run in dual channel mode (nothing whatsoever to do with dual core processors) but since dual channel ram gives such a tiny performance boost it's usually better to go for the extra ram and stay single channel than to go dual channel and have less ram.

They don't need to be in pairs but if they are they'll run in dual channel and give twice as much bandwidth, thus increasing the speed of the computer.

Marty_J

marms wrote: »

They don't need to be in pairs but if they are they'll run in dual channel and give twice as much bandwidth, thus increasing the speed of the computer.

The difference in performance would be negligible at best.

rdpro

Dual-channel technology was created to address the issue of bottlenecks. Increased processor speed and performance requires other, less prominent components to keep pace. In the case of dual channel design, the intended target is the memory controller, which regulates data flow between the CPU and system memory (RAM). The memory controller determines the types and speeds of RAM as well as the maximum size of each individual memory module and the overall memory capacity of the system. When the memory is unable to keep up with the processor, however, a bottleneck occurs, leaving the CPU with nothing to process. Under the single-channel architecture, any CPU with a bus speed greater than the memory speed would be susceptible to this bottleneck effect.
The dual-channel configuration alleviates the problem by doubling the amount of available memory bandwidth. Instead of a single memory channel, a second parallel channel is added. With two channels working simultaneously, the bottleneck is reduced. Rather than wait for memory technology to improve, dual-channel architecture simply takes the existing RAM technology and improves the method in which it is handled. While the actual implementation differs between Intel and AMD motherboards, the basic theory stands.

(shamelessly copied from Wikipedia)


Sisoft Sandra will do a decent benchmark http://www.sisoftware.net/

weegie.geek

Indeed it will, and it'll show that there's a negligible difference. 10% if you're lucky.

In theory it should double, but in practice it doesn't get near that.