Introduction
Sapphire's special version of the X800 GTO is called X800 GTO². As you can see in the following picture it uses an R480 core, which is also used on the X850 Pro, XT and XT PE.
The GTO² is a special product from Sapphire only. Neither the regular GTO, nor the GTO Ultimate use the unlockable chips. If it does not have ² in the name, it can't be unlocked.
UPDATE: The X800 GTO cards from Connect3D can also be unlocked, see page 4 of this article.
http://www.techpowerup.com/articles//overclocking/vidcard/127/1
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