There are three possible reasons why your computer may not recognize your new RAM:
1 – The RAM sticks you buy are not designed to work with your computer’s motherboard. In my opinion, this is the possible cause of your problem. You didn’t mention the computer’s model number, but since it comes with two 1GB sticks installed, I guess that the RAM it needs is either DDR or DDR2.
Since you bought 4GB sticks, they are more likely to DDR3, and if so, they are almost certainly not compatible with your computer’s motherboard. You can still buy 4GB DDR2 RAM, but I bet one dollar against a penny you buy is DDR3.
2 – You have purchased the correct RAM type, but you are not getting the sticks to properly sit in the RAM slot. This is certainly possible, but I have severe doubts about this being the case here.
3 – Even though they are new when you buy them, one or both of your new RAM sticks are faulty. (This isn’t easy, in my opinion.)
Again, possibility number one is due more likely because your computer won’t recognize the new RAM.
If I were you, I would try returning the RAM you bought to Best Buy and see if they give you a refund. I’m not sure they will, but it’s worth a try.
Next, I went to www.Crucial.com and used their free System Scatnnerto to determine precisely what type of RAM your computer uses. Just follow these steps:
1 – While at the Crucial homepage, agree to the terms and conditions by checking the box, then clicking on download scanner.
2 – Once the System Scanner utility has been downloaded and installed on your PC, run it, and make a note of the correct type and specifications for the RAM your computer requires. Also, pay attention to the maximum amount of RAM your system can handle. Buying more than that won’t do you well, and it may even keep your computer from booting into Windows.
3 – Either buy RAM that directly matches the specified parameter from Crucial (you can buy it right from the scan results page) or buy RAM elsewhere that exactly matches the parameter specified by the System Scanner utility.
I hope this helps you. Good luck!