First of all, my systems specs:P4 1.7 GHz256 MB RDRAM (600 MHz, 2x 128 MB)60 GB HDDGeForce 2 Pro (upgrade pending on the video card too :-))I'm going to get another 256 MB of RAM, but I need some advice. First of all, it's my understanding that the RDRAM I have must be run in pairs, so I would have to buy two more 128 MB modules.Do the new modules have to be the same speed as the current ones (600 MHz)? Looking around the web, I wasn't even able to find 600 MHz modules for sale. So can I buy two 128 MB 800 MHz modules and add them, or should I get rid of the currently installed 600 MHz modules and get 512 MB of fresh memory?Also, should all the modules be by the same manufacturer? (And how can find information on which manufacturer made the modules I have installed now?)Is there any way to know for sure whether the memory has to be installed in pairs? I read this somewhere, but I'm not sure where, or if it applies to my system.Finally, is there a good guide explaining RDRAM upgrades, the pairing, bus speeds, and so on? I have read guides on RDRAM, but they usually run a bit too technical for me. :-(Thanks,Martin767 fetishistIt's a lot like life and that's what's appealing

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Thanks, that cleared it up somewhat.The configuration as it is now is:1: 128 MB (600 MHz) module2: EMPTY3: 128 MB (600 MHz) module4: EMPTYIf I fill up slots 2 and 4, does it have to be the same kind (128 MB, 600 MHz)? Or can I put 800 MHz modules in slot 2 and 4? Can they even be a different size, say, 256 MB each?Thanks!Martin767 fetishistIt's a lot like life and that's what's appealing

I would say that you could use the 800's or higher in the two empty slots, just as long as they are matched. I don't think you are going to find the 600's anymore.Also make sure you buy the correct set for the Intel driver. The 850 I think is the one with the part no. with the E at the end. One easy way to do it if you have a brand name computer or know the MOBO, is to use their help searchers.