I'm thinking about purchasing an additional RAM, probably 512 MB PC3200, but I'm in doubt. First, my processor is 3Ghz HT that I bought about 3 months ago along with 2 x 256 MB DDR RAM PC3200. When I purchased it , the seller told me something about 'the memory should be identical and must support HT'. Is it true that buying memory for HT should be selective? How can I know if the new memory will match my current system?
Also, how much will the RAM costs approximately?
Please note that I'm going to purchase only 1 card
Ok firstly HT is a function of the processor and doesnt have anything to do with the RAM. What I think he was talking about was dual channel mode, this is when two identicle 64bit RAM channels are combined to create a single 128bit RAM channel.
This doubles the effective bandwidth of your RAM (doubles its speed if you will).
It is similar (at least for the perposes of this explanation) to a RAID0 array in that it sends half the data to one RAM module and the other half to the second RAM module.
The modules have to be the same size (and preferably the same make/model) to work in dual channel mode. This is why nowadays you see a lot of 'matched pair' kits guarenteed to work in dual channel mode.
Thanks JammyDodger, I currently have that kind of pair RAM that you talked about. Since I'm thinking about adding 1 RAM card, what kind of RAM card should I buy? Must it still be the same as the pair I currently have (same size same manufacturer)?
If I purchase another card that is 512 and same speed (PC3200) but different manufacturer, can the previous pair of cards still be recognized as 'dual channel'?
No I will not be recognised as dual channel, the problem here is that you need equal numbers of RAM modules with equal density. I.e you need 2x256MB or 2x512MB or 4x256, 4x512 etc etc...
You cannot use odd number of RAM modules because the banks need to be equall. (Technically it should be possible to use 2x256 in slots 1&2 and then 1x512 in slot 3 but this does not work...im sure there is a good reason for this).
If you have 2x256MB modules now you need to get either 2x256 or 2x512 for it to work in dual channel mode.