|Don't buy ram randomly, especially online. |
Ram that works in another mboard , or any ram you buy or have lying around, may not work properly, or sometimes, not at all - even if it physically fits and is the right overall type (e.g. SDram, DDR, DDR2, etc.; PCxxxx, xxx mhz) for your mboard. In the worst cases of incompatibilty your mboard WILL NOT BOOT all the way with it installed, and the mboard may not even beep - the ram has to be compatible with the mboard's main chipset, or in the case of recent mboards, compatible with the memory controller built into the cpu.
See response 5 in this for some info about ram compatibilty, and some places where you can find out what will work in your mboard for sure:
Correction to that:
When you look up ram for a brand name system on some sites, the modules may have only an oddball ID string (part "number") specific to the brand of system (e.g. the Kingston web site). Other ram may work fine, but that site doesn't specify that.
Ram that doesn't have an oddball ID string specific to the brand of system may be listed on other sites, or if you determine which actual mboard model your brand name system has (in this case, HP did not make it) , ram that doesn't have an oddball ID string specific to the brand of system will be listed - you have more possibilities to choose from.
Once you know which module ID strings work in your mboard, you can get them from anywhere you like that has ram with those ID strings.
It's quite rare for you to see pictures of the ram in ads that shows both sides of the module, or for it's specs to mention whether it has chips on both sides, or 16 chips (no more than 9 fit on one side; most have 8 on one side).
The Kingston site, for one, has the specs available to look at for most modules that don't have an oddball ID string specific to the brand of system that tells you the number of chips and diagrams that show you both sides of the module. However, Kingston has replaced the ones with 16 chips with ones with 8 in some cases, without changing the specs, the ones with 8 often won't work in older systems/mboards, so you're better off finding ads that show both sides, or that state is has chips on both sides or 16 chips.