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Ok , I am planning to buy a 1 GB RAM to supplement my computer's old 512 MB Ram . Is it advised to use it side by side ? I am sure the 512 MB RAM Is not exactly in good condition as it is 4 years old . Will it affect he performance ? Which is better - with both RAM's or the new RAM only

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If they are different speeds, you will be limited to the speed of the slowest one (or they may not work at all together). Other than that, I don't think so. (and even if you do run the new memory at a lower speed, you probably won't notice the difference)

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It'll either work or it won't. The newer RAM will slow down to match the older RAM's speed. Your motherboard might complain, and in some cases, there's a BIOS setting to tell RAM to ignore mismatches.

It's better to have the same type of RAM in your machine, but (for example) I have had a case where I had 2 x Kingston and 2 x no-name-brand in the same box, because 4 x Kingston just didn't work together.

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One might also check if mobo supports dual channel memory. – Marcin Gil Dec 1 '09 at 8:07
Good suggestion. – user3463 Dec 1 '09 at 11:25
By dual channel memory do you mean 2 memories ? There are 2 slots , so shouldn't it support ? – Nishant Dec 1 '09 at 12:21
Dual channel means that if you put 2 similar RAM sticks to 2 dual channel slots the memory will go faster as it can be read/written in parallel. See – Marcin Gil Dec 1 '09 at 12:24
Dual channel needs to be the same size to get the best performance. However, even when using mismatched sizes that can't take advantage of dual channel, you're still likely to see better overall performance just because you have more RAM. – Rudedog Dec 1 '09 at 17:25

Your motherboard may not let you mix RAM sticks of different sizes. Check with the manufacturers recommendations.

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i think this piece of advice is a holdover from the 486 days. the last motherboard i saw that did this used 30-pin RAM; we're now... what, 5? 5 generations of RAM tech beyond that. (ok, maybe that motherboard had 72-pin RAM instead of 30-pin. still. for modern motherboards, this shouldn't be a problem.) – quack quixote Jan 3 '10 at 18:12

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