1. You probably wouldn't notice any speed difference, mainly because even if your ram is set at a faster speed than your cpu, your cpu would hold it back, and vice versa.
2. I don't know whether that is true or not, first of all. Second of all, DRR667 = PC5300, so yes, it will support your existing memory.
I own a Dell Dimension 8400. The CPU is the Pentium-4 630, which has a speed of 3.0 GHz and 800 MHz FSB (2MB L2).
There are 4 DIMM slots. Currently, a total of 3.0 GB DDR2-400 is in those slots. The existing configuration is 2x1024 along with 2x512, of course.
If you're wondering why I have 3.0 GB RAM, this is because the machine arrived from factory with 2x512. I later added 2x1024 -- again, all of this is DDR2-400. I do think the 3.0GB is overkill as I have learned from much benchmarking at both the 2.0GB and 3.0GB levels.
I have two questions.
(1) If I were to replace all of this with 2x1024 of DDR2-533, what sort of speed or efficiency increase is noted (if any)?
(2) Will my existing PC2-3200 modules totaling 3.0GB ever be useable in a future AMD-powered machine? I hear that AMD will soon support DDR2, however, I also read that the minimum AMD will support is DDR2-667. Is this true?
Thanks in advance.