when putting in dimms do they need to be exactly the same or just the same size ie.128 mb?

Answer 1

The first two answers apply but here is the kicker, if you have a 133HZ and a 33HZ stick at 128 megs each the fastest it will go is 33Hz so you are gaining memory but losing speed. also some mother boards will lock up with mismatched memory. It has been from my experince to have a chip not even work on some motherboards but it never hurts to try it if you are just looking for more memory, most of the time your looking to boost the computer speed as well as the amount of Memory.

Answer 2

They don't need to be the same size in MB's. They do have to be the right type of memory though. You have to use the type of RAM that your motherboard calls for. They do not have to match in size.

Answer 3

They can be the same size or not. But, if your slot has dual channel, It is better to put exactly the same DDR. Manufacturers do have their differences.

Answer 4

somewhat vague but I'll take a stab at it.....

If you're running standard ddr you want both sticks to be rated for the same speed.

However, if you're running dual channel memory it's best to have a matched set of sticks

Answer 5

Double Data Rate DIMM [DDR-DIMM, DDR DIMM, or DDR1] utilizes the JEDEC standard for Double Date Rate [DDR I] SDRAM.
DDR SDRAM:....Double Data Rate SDRAM [DDR200, DDR266, DDR333 are standard]
.........PC1600 (DDR-200 SDRAM); Clock Speed: 100MHz, Data Rate: 200MHz, Through-put 1600MB/s
.........PC2100 (DDR-266 SDRAM); Clock Speed: 133MHz, Data Rate: 266MHz, Through-put 2100MB/s
.........PC2400 (DDR-300 SDRAM); Clock Speed: 150MHz, Data Rate: 300MHz, Through-put 2400MB/s
.........PC2700 (DDR-333 SDRAM); Clock Speed: 166MHz, Data Rate: 333MHz, Through-put 2600MB/s
.........PC3000 (DDR-366 SDRAM); Clock Speed: 183MHz, Data Rate: 366MHz, Through-put 2900MB/s
.........PC3200 (DDR-400 SDRAM); Clock Speed: 200MHz, Data Rate: 400MHz, Through-put 3200MB/s

All you really need to know is that as long as you use the same PC type you can plunk in whatever you want if your board will support it.

Common types listed in link.