How, hoepfully this is an easy question. I have a Compaq Presario. It has 64 MB of RAM, and I want to add at least 64 MB more. I can't figure out how to tell what kind of RAM it is however without opening it up. It's just a pain to disconnect all the cables and open it. In fact, I had it open this morning and cleaned all the dust out of it. I looked at the RAM, and it said "100MHZ DIMM." At least that is all I wrote down. Now when I looked to buy some RAM, I see there is SDRAM and and DDR. I have read Compaq's use a lot of proprietary hardware, this doesn't include the RAM does it? The machine was probably manufactured circa 1999/2000 (it's a Celeron 533). My guess it that it is SDRAM, but I would like to know for sure. I tried Belarc, and it just reports 64 MB DIMM. The Compaq guide just calls it a DIMM when it addresses upgrade. The Compaq site sucks now that HP bought them out (not much Compaq stuff, or it's hard to find). Would it be safe for me to buy PC100 (or higher) SDRAM, or should I make sure what I have first?

Goto www.crucial.com and select your model.

Yep. It's perfectly alright to use PC66/100/133 SDRAM with that Celeron. RAM is backwards compatible and in your case will run at the Celeron's FSB speed of 66 MHz. Just make sure you don't order DDR RAM or RIMM RAM. 168 pin SD RAM is what you need of any of the above stated speeds.

Thanks for the help guys. That crucial site is a great help, and I have it book marked now. I went today to buy the RAM. At Best Buy they had 128MB PC 133 SDRAM for $17 (with mail-in rebate). However, when I read the package it said that it should NOT be used in systems that use PC100 memory (said it wasn't backwards compatible) or systems with the Intel 810 chipset. Well, I have both of those. They also had 128MB PC 100 SDRAM, but it was $45 (no rebate). Wow, that was expensive! So I went to another store and found 128 MB PC100 for $27. Installed it, and it works great.