AMD's first DirectX 11 graphics chip won't appear in products you can buy before November, despite being demoed more than a month ago.

AMD first showed off its DX11 GPU - codenamed 'RV870' - at the Computex show in Taipei, Taiwan early in June.

To be fair, AMD didn't say when the ATI-branded GPU would go on sale beyond stating that it would appear "before the end of 2009". This gives it plenty room to release the part early or late, according to necessity.

Some pundits have speculated that the chip could be out as early as September, but German-language site ATI-Forum reckons RV870 won't appear until November, at the earliest. It said the yields chip foundry TSMC was getting with its 40nm process aren't yet high enough for AMD to consider mass-producing RV870 in an earlier-rather-than-later timeframe.

Of course, AMD's first DX11 GPU will not a be massive seller straight away - too few DX11 games are available for that - so the yield issue may not matter per se. More likely, it wants to make sure that the working 40nm chips coming off TSMC's production line are products it hopes to sell in greater volumes than RV870 will sustain.

DX11 will be part of Windows 7 - due in October - and is expected to be retrofitted to Vista with a Service Pack update shortly afterwards. Windows 7 will make use of the framework, using the API's CPU-on-GPU workload shifting to accelerate processor-intensive tasks.

DX11 also brings tessellation and with it the promise of much more complex geometries - essentially, more detailed models than we've seen before. ®