The RSX graphics part which will sit alongside the Cell CPU at the heart of the PlayStation 3 is still under development, according to NVIDIA chief financial officer Marv Burkett, with E3's tech demos being run on a different NVIDIA chipset.
Speaking at the JP Morgan technology conference, Burkett confirmed that no silicon has yet been created for the RSX - which is being designed by NVIDIA, but will ultimately be manufactured by Sony itself.
The tech demos shown off at E3, then, were all run on a different piece of hardware - a forthcoming desktop PC chip which, according to Burkett, shares some of its capabilities with the RSX.
The news is somewhat unsurprising, given that the first consumer application of the chip in PS3 won't be on shelves for another year, and seems to confirm assertions from Sony's Phil Harrison and a number of third-party developers at the show that the currently available PS3 hardware is running at lower performance levels than will be achieved in the final unit.
Graphics chips are often among the very last pieces of hardware to be finalised in console development, largely due to their complexity. Developers at the show also noted that few, if any, studios have Xbox 360 development kits with final ATI graphics hardware in them