I recently bought 256mb of memory for my HP Pavilion 510w. I put it in the computer but it doesnt show that it was installed. I know I put it in right. Any one have any ideas what the problem could be?If installed correctly, the most likely cause is that you got the wrong memory, or the new RAM is damaged. Most of the time, it turns out to be the wrong memory. What did you get and from where. SPEED alone is not enough in choosing! Chip density and other characteristics are critical.

On the web page for your model at www.crucial.com it clearly states:

Important information about your computer
Your system only supports modules made with a SPECIFIC type of chips. While you might find what appears to be the exact same memory for a lower price elsewhere, the CHEAPER memory might not work in your system. The Crucial Memory SELECTOR only selects memory that is 100% guaranteed compatible with your system or we'll give you your money back! Learn more about chip density, memory prices, and compatibility here.

If you can, I would return it immediately. Crucial always has REASONABLE prices, lifetime warranty and GUARANTEED compatibility. What else would you be looking for?

http://www.crucial.com/store/listparts.asp?Mfr%2BProductline=HP+-+Compaq%2BPavilion+500+Series&mfr=HP+-+Compaq&tabid=AM&model=Pavilion+510w&submit=Go
Alright, I'll see if I can return it and I'll check out that site, thanks.Out of curiosity, what exactly were the specifications for what you got?