I have a computer that is used for gaming and work. Dell XPS 400. It initially came with 2x512mb sticks or RAM installed. I went out and bought 2x1gb RAM. Installed them. Everything seems fine. The computer recognizes them along with the 512 sticks. I am wondering though if having those two sticks of 512 will have a negative impact on the 2, 1 gig sticks. Meaning - would i get better performance if I remove the 2 sticks of 512 and only have the two sticks of 1gb installed. I have recieved no errors but I dont see a significant amount of difference in performance with 3 gb of RAM than I did with just the 1gb. Please help and thanks in advance!!!

Sometimes the difference is the amount of ram available. The major difference will be the refresh rate and the timing settings you assign in Bios. This page might help explain that: http://www.amd.com/us-en/Processors/ComputingSolutions/0,,30_288_13265_13295%5E13335,00.html

Having said that, when two different sets of memory at different refresh rates and timing run together, the computer will always use the lower settings.

Now, having said that, adding ram allows your computer to "breath" better meaning that if Windows recognizes the extra memory, it will not cache to disk so often, and multiple applications running simultaneously behave better. If this is what is meant by performance, you will have better performance and perhaps a slight speed tweak because it doesn't have to swap memory.

There are two further considerations in relation to speed, if that is what you are after especially in relation to games. The first is a faster rated processor with a larger onboard cache and the second is the video card with faster throughput and a large amount of memory (depending on the game). More often than not, upgrading both of those items (and this depends on the motherboard) will increase your speed. You can increase the front side bus (but on a Dell this is not advisable) and you can dig some extra speed out of the processor. However, you will run the machine hotter, and the life of the system as a whole will decrease.

In short, putting more ram in your system is a good performance upgrade (be sure of the timings given for the new ram), but it will not always yeild a visible speed increase.