HIS HD 6870 Turbo cards are factory overclocked with a warranty. Now let me clarify something here. I said the HIS HD 6870 Turbo which is what we reviewed recently. HIS's Turbo X takes things to an entirely new level. The HD 6870 reference clock is 900MHz on the core and 4.2GHz on the memory. The HIS Turbo version of that card tweaks things to 920MHz on the core and 4.48GHz on the GDDR5 memory. With the IceQ X cooler, HIS takes things to the X level and jacks their card up to 975MHz on the core and 4.6GHz on the memory. That's quite a bump.
Slow computer got you down? Maybe a hardware upgrade should be in your cards, if so this guide to the Fundamentals of Upgrading a PC is an invaluable read. PCSTATS Tips