It shouldn't be a problem, but what RAM and how many modules?
i have 1 kingston ddr2 512mb 533mhz single sided.. and i have 1 new kingston 1gig ddr2 533mhz double sided.. i didn't notice that the new one is double sided.. i have only two dimm sockets. is there any problem if i mix them?
well if it doesnt mix (timings etc) it can cause corruptions - wouldnt call "nothing bad can happen" "best answer"
rams golden rules - most matched, and least ammount of sticks
The modules are identical, except for the number of chips on them and they run at 533 MHz; it isn't like if the OP was using modules with high voltage and aggressive timings. Given the info that was provided, nothing bad can happen.
If it works, don't worry about it. Bad things can happen when using overclocked memory that requires a lot of voltage, e.g., 2.3V instead of 1.8V, etc. I've never seen issues with DDR2-533. However DDR2-1066 often causes issues, particularly when using 4 modules.