SATA vs PATA question

Does using a PATA device on an otherwise all-SATA system slow down anything?

I was thinking of dumping my beloved Plextor PATA DVD burner, in favor of a new SATA variant.

If it means more speed for the overall system, that would be even better.

no slow downs at all

Even with HDs it really means nothing. It all has to do with the internals. There really isn't anything that can saturate a SATA or IDE spec.