Well, my current 1GB of ram with two 512mb sticks have a Cas Latency of 5. Wouldn't it conflict with this Patriot ram since it has a Cas Latency of 5? Remember, I do want 3GB of ram, not 2GB, so I'm not going to remove the current ram in the system and put completely new ram. I'm also running on an AMD system, not an Intel. If you can, I would stick with the same memory. Most of the memory that is made by the same company will tend to work well with each other. You're adding another 2GB for a totla of 3GB? But that doesn't mean different memory won't work. As such as recomended for the Patriot memory, if you pop it in, it will run at the speed your current memory is at if it is slower than the Patriot. Also when it comes to latency, I can tell you that you will not see a difference. The cost to performance is so small it isn't worth it. I remember reading on a test of Cosair high speed memory with their Select brand. In a game they gained another 2 FPS, but the memory cost like $300 more. Unless you are overclocking, or a spead freak and must sqeeze everything out of it, you will not see any performace difference over a low latency chip over one that may be slightly higher. Your memory you have now is 5-5-5-18 The memory you looking to get is 5-5-5-15 And the memory sugested is 4-4-4-12 Any of these chips will work... http://www.newegg.com/Product/ProductList....+800+(PC2+6400) In the end is comes down to reputation on reliability of brand. How do they do their quality control and tests on their modules. Most of the chips on the memory modules are from the same companies, Samsung & Infineon being the most popular.