Ok, im gonna do it short:
1. the 1Gb Ram got a latency of 3CL² (if you find a 2,5er, send me the Link plz
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2. 512MB got mostly 2,5CL² (2,0 only in 100Mhz mode or they a fu***ng expensive)
3. 256MB mostly 2,0CL² (Like Kingston)
4. lower CL = faster read/writing the memory
5. DualChannel mode = much more faster
²= (CL = CAS Latency)