Nvidia forced to disable chipset PCI prefetch:
http://www.fudzilla.com/index.php?option=com_content&task=view&id=10222&Itemid=1

"The problem with this is twofold. Firstly, it means that just about every single Nvidia chipset from the nForce 500-series and onwards is affected and as such, PCI prefetch has to be removed from all retail boards and every single BIOS upgrade that contains the PCI prefetch code has to be removed from the Web. This also means that all Nvidia partners have to release BIOS updates for every single Nvidia motherboard from the nForce 500-series and onward."

"For consumers, this means that they'll get very poor PCI performance, so if you're using any PCI cards in your Nvidia-based motherboard, don't upgrade to the latest BIOS, as it will reduce the performance of the PCI bus. This isn't going to be popular with a lot of users out that that have already upgraded their BIOS, as this "feature" has already been implemented by some motherboard manufacturers going back a couple of months."

Ya, i made the big mistake of getting an nvidia board when i did my big upgrade a year ago.  Along with going 64bit Vista, it's taken a year for it to become stable.  But that is after it frying several chips of ram and my having to rma the mobo once during this time.  Also, swtiching from an nvidia 8800gtx to the 4850 really seems to have made my system very stable.  I seriously haven't experienced a hard lock or freeze for at least 2 or more weeks now which previously was unheardof.

With ram prices the way they are, i've half considering to replace my mobo with an Intel board which will allow me to get a second 4850 in crossfire and upgrade the memory to 8gb.  Nice little upgrade.    The old parts can go into an old case i have and have a very nice second computer to use for whatever.

My question is, why? You mention that they are doing it but for what reason? To give performance boost somewhere else? Cause of some legal trouble?

Did some digging and found it was lawsuit issues.
http://www.reuters.com/article/pressRelease/idUS131836+22-Sep-2008+BW20080922
And from other things that I read this company just hold the patent but doesn't do anything with it. What a bunch of asshats.