Complex sentence: To perform properly, the chips were dependent on sizable amounts of secondary cache ram being present on the motherboard; without it the Pentium OverDrive was only a trivial amount faster than an DX4.
Split into simpler sentences: To perform properly, the chips were dependent on sizable amounts of secondary cache ram being present on the motherboard. Without it, the Pentium OverDrive was only marginally faster than an DX4.