Complex sentence: The first series were the V6 and V8, with 32MB and 128MB of RAM respectively; the V10 and V12 had double the geometry performance of the older V6/V8, but were otherwise similar.
Split into simpler sentences: The first series were the V6 and V8, with 32MB and 128MB of RAM respectively. The V10 and V12 had double the geometry performance of the older V6/V8, but were otherwise similar.