Nvidia's difficulties in providing full DirectX 10 support are largely due to Windows Vista's new architecture, says the development boss.

Dwight Diercks was speaking to US site PC Perspective .

Diercks manages Nvidia 's Software Engineering arm and explained some of the difficulties the company has experienced in developing drivers for the Vista graphics engine. The problem has centred largely around developing software to power SLI, Nvidia's dual-graphics tech.

It seems XP would let Nvidia's ForceWare mind its own business, but Vista's new graphics model isn't quite so accommodating.

Nvidia created two SLI components for XP - handling DirectX and OpenGL rendering separately.

So with Vista, Nvidia needs different drivers for each combination of DirectX 9 single or dual card, DirectX 10 single or dual card and OpenGL single or dual card.

This is new ground for Nvidia - Diercks claimed in his interview that each of the six drivers is roughly 20 million lines of code long.

He also said that Nvidia would be releasing a ForceWare Vista update once a month - the same regular update cycle that ATI uses. Nvidia may also plug other problems if necessary in the intervening time.

Given this cycle, it seems Nvidia is planning on getting SLI working with GeForce 7 cards during March and with April as a target for full DirectX 10 support within Vista.