Vista Upgrade boosts video memory for dv6000t?

I recently upgraded my dv6000t to Vista and it now states that I have 399 MB of video memory for my Nvidia Go7400. I know the card has only 128 MB dedicated and was supposed to have 128 MB shared with the system ram for a total of 256. What is the deal here? It now says I hve 271 MB shared with system memory and 128 MB dedicated. Is this really the case or just an error? Could this be the result of Vista or the new Nvidia drivers? Anyone else see this happen when they upgraded?

 

When Microsoft rewrote the Windows driver model for graphics cards under Vista, they included a mechanism to allow the OS to control shared memory for graphics chips that use it. Under XP, only the graphics drivers or the BIOS could control the amount of system RAM allowed to be used by the graphics chip. The Nvidia, ATI, and Intel drivers for Vista all give Vista control over the amount of RAM to be used by the graphics card, and Vista in turn uses its own algorithm to determine how much to make available... and the algorithm has no relation to what the graphics card manufacturer originally intended. It's quite a bit higher, but it's allocated dynamically, and you're not likely to run into a situation where it's all used.

Hope that helps. If you really care to learn how it works, there's a post I made somewhere here with the exact formula used by Vista and a link to the Microsoft whitepaper.