A source familiar with Advanced Micro Devices product planning denied the rumours that the first chips code-named Ontario that combine x86 cores as well as graphics processor unit on the same piece of silicon and designed for low-power would have abnormally high power consumption.

"Categorizing AMD Ontario as 18W or 24W is not reasonable and well outside the margin of error," a source close to AMD said on Wednesday.

Earlier it was reported that AMD's first processors based on Fusion design aimed at ultrathin notebooks and netbooks would consume 18W or even 25W. However, this seems to be complete incorrect and the final products will be massively more power efficient than the rumours claim.

The Ontario features one or two x86 processing cores based on the code-named Bobcat micro-architecture (a technology that AMD has been developing for many years now) as well as DirectX 11 graphics processing unit from ATI. The Bobcat is an AMD approach to the low-power computing, hence, the direct competitor for Intel Atom. The Bobcat is an out-of-order execution processing core, hence, it will by definition consume slightly more energy than Atom. AMD promises that the Bobcat is sub-1W-capable, hence it will be possible to use it in low-power devices as well. Given the two facts, it is hard to expect the first microprocessor offerings powered by Bobcat to consume 18W of power.

Although the source did not disclose any actual power consumption details regarding the first Fusion concept-based chips, it should be noted that based on documents seen by X-bit labs the dual-core code-named Llano processors - which feature high-performance Phenom II-class x86 engines along with high-end graphics cores - were meant to fit into 20W thermal envelope thanks to a plethora of power consumption trimming techniques implemented by AMD microprocessor and graphics processor engineers into the design.

Although at this point nothing is set on stone, it is unlikely that that code-named Ontario and Llano processor families will overlap tangibly in terms of performance or power consumption.

AMD did not comment on the news-story.

Tags: AMD, Fusion, Ontario, , Brazos, 40nm, zacate, Llano