What is the best combination of RAM from the following?

eatingrich

Hey folks,

I've come across some extra RAM, and want to get the best possible combination from it and the existing RAM I have for my girlfriends computer. She uses it for work, and uses Sibelius, QBase and similar music programmes.

So, she currently has two sticks of PC2100 256MB RAM. Her mobo can only take up to two sticks.

The new RAM I've been given is two sticks of PC2700 256MB RAM, so a straight swap would speed it up slightly, right?

I ALSO have one stick of PC2100 512MB ram and another stick of PC2100 256MB Ram.

So, which would be the best, fastest combination for her? I'm leaning towards the PC2700 pair as its faster than the PC2100 and I'm not sure how much she'd need the extra 256mb ram compared to say, a new graphics card.

On the other hand, if I put the 512MB stick in, would it work quickest with the PC2700 stick or another PC2100 stick, so she could have 738MB RAM?

How much difference does it make when your RAM is made up of different sizes and PCxxxx speeds?

Cheers guys, hope everyone had a good xmas!

Dowaco

It depends what processor she has and if the motherboard supports dual channel.

If the processor front side bus runs at 133 MHz, then PC2100 RAM (DDR266) is right for that PC, swapping to PC2700 (DDR333) will not make it run faster unless you plan to overclock. If it runs at 166 MHz or higher, then PC2700 will make it run faster.

If the motherboard supports dual channel memory operation, then you must use two sticks of paired memory to activate that feature.
If you have dual channel capability it is better to use two sticks of 256 than a mismatched pair since dual channel doubles the bandwidth of the memory.
Some older motherboards with AMD processors do not have dual channel capability. In that case, having one stick of 512 and one of 256 would be the best combination since it gives the most memory (768 MB).

Applications that need a lot of memory might benefit from having 768 of slower RAM, while most other applications would run faster with a matched pair (2x256) running in dual channel mode.

Hope that helps.

eatingrich

thanks alot, superb answer! I didn't put down motherboard specs as I didn't realise it made such a difference so thanks for covering all the bases, I'll have to pop on her computer today and find out all the specs! Thanks again!

eatingrich

Hey, well, it seems her PC runs at 166mhz bus, according to Belarc Advisor, but it also doesn't support dual channel, meaning you get nothing extra for using twin sticks.

So...is it best to use the 728MB combination, with the 128mb at PC2700, or just stay at 512MB with both at PC2700 as at least it will be optimum for the mobo even if it doesn't have dual channel?

Also, it seems the Bus on my own mobo runs at 100mhz, so whats best then?! It doesn't have dual channel support either, so I'm thinking just whack on as much RAM as possible!

Thanks again!

eatingrich

Apologies for the constant updates, but I've found out the mobo is an ASUS AV400-MX, and the manual says it runs at FSB speeds of 400/333/266/200 and is compatible up to PC2700.

So now I'm confused as to what Bus speed its actually running at. Is the bus speed mentioned by Belarc Advisor the bus speed and if so why is it 166mhz and not one of the speeds mentioned in the manual.

Sorry I know this is probably basic CPU/RAM/Mobo knowledge but its just abit confusing, how do I find out what speed the FSB is running at?

Thanks again!