Hi .Elocor, well as you can see from my rig, I have just installed the same card as you. I originally had ATI 5770, but as I am into dvd and bluray, I wanted to back up my collection and the software I use is dvd fab , which is written to operate with Nvidea and hence the change.
I have been watching your post and waiting to see if you got a solution to your problem..I dont do games and therefore dont have the same issues as you, But copying bluray needs lots of processing and it seems to be copying some bluray's. I must admit sometimes when I start up win7 ultimate, on a few occasions it doesn't load and i have to let windows check, and then all works ok.I have also had on a few occasions the graphics stop working when on the computer and a few times where the system loads up and does not install the grahics. I have also tried both the drivers that you mention. I suppose the same as me, you have read lots of people having problems with this card on different forums..Well sorry this doesn't help your problem, but at least your not on your own. Being a newbie I did not know you can update the card bios, maybe absic can advise me on this, as I have seen on Toms hardware site, where someone else was having the same probs and was advised not to update..