adding ram: 512MB installed, 768MB maximum

I just got my bio information and it says the maximum memory is 768MB


I already have 512MB installed in the first slot, my question is, can I install another stick of 256MB in the second slot or do you have to have matching ram?

if I install another 512MB than that would be a waste of money if my max is only 768

it came with the one stick of 512 already installed, and I have 3 slots.

help and thanks.

I would like to buy it this week, so I need to know if I can have two sticks of different sizes installed.

 

What are your system specs? With an upper limit of 768, that suggests to me that you may not have a lightning fast CPU. If that's the case you may not notice much improvement installing more memory above 512. If your nunning an NT flavoured OS, I'd suggest loading a few programmes (up to what you're likely to have running at one time) and check your RAM usage in the task manager performance tab. If your memory usage doesn't (or extremely rarely) go beyond 512, then you may not see much improvement in adding more memory. The memory speed will be limited firstly to what the M/B supports (PC100, PC133, DDR 2100, DDR 2700 or DDR 3200 as way of example) and secondly to what the slowest stick installed is.
Further to what Steve Jones says. Generally PC66, 100 and 133 RAM is interchangeable and DDR 2100, 2700 and 3200 RAM are interchangeable with exceptions including make and latency specifications, among others.