Got Apex? put up a dual review of X800 GTO based cards from HIS and Sapphire.

The stock versions of the HIS and Sapphire cards perform well, of course being of the same core, clock, and memory speed they perform almost identically. The true value of the cards comes out with the overclocking, the HIS card automatically improves 8% with some headroom to go a bit further. HIS states that it can go up to 540 and probably further. The Sapphire card performs great once you unlock it's full potential with the extra four pipelines, as shown there is a massive increase in many cases, up to 50% in a few. Sapphire definitely has an edge with the unlocking ability.

X800 GTO - Sapphire and HIS