This has probably been discussed before, but...
I'm a little at a loss to figure out how DDR2800 CAS 5 is going to
perform better than DDR400 CAS 2.5.
CAS (Column Address Strobe) timing isn't really ver y critical although
you'll find many people make a big deal of it. It's just one of many
things associated with timings. IOW's, ram witth half the CAS timings as
another isn't going to be twice as fast. The overall speed of the ram is
readily depicted by its PC number. PC3200 means it provides a bandwidth of
3200MBps, and PC6400 ram provides 6400MBps In the end, that's all that
really matters. And in system overall performance, even that isn't really
that important since normally 90% of all ram data request actually get
serviced by the CPU L1 or L2 cache thus leaving the ram speed almost
meaningless. If you want to see what I'm talking about, go into the bios
and disable both L1 and L2 caches and then reboot. Be ready for a really
slow system by comparison.