FYI I posted this in the 5/6/7/8/9/200/400/500 Series Trouble Shooting/Updating/Install Guide for Drivers thread, but nobody responded for a week because nobody saw it (I'm hoping). So I'm creating a new topic! Sorry if that's not cool.
 
Since posting I've reinstalled a fresh copy of Windows 7, so I don't think this had to do with any weird program conflicts or anything. I'm currently running the drivers EVGA provided me on a disc that came with the graphics card.
 
What follows is my original post:
 
I'm having trouble upgrading my drivers. I have the 266.something version installed and everything (except updated games) works pretty well, but when I try to upgrade to the current WHQL drivers, the following things happen:
 
1) Windows 7 (Home Pro) starts normally, shows properly-rendered "Please Wait" and "Welcome" splash screens at correct resolution with animations
2) The screen turns a solid blue (not BSOD blue) and the system hangs here. Sometimes it changes to a black screen and restarts.
 
I've followed this guide to the letter, also uninstalling EVGA Precision since it seemed like it might be causing a problem. Unfortunately, the problem persists, and I'm forced to system restore back to the 266.something version (if this matters, I can update after I system restore again).
 
Does anyone have any tips for what to do next? I'm sort of out of ideas. The card itself is a GeForce GTX 480 that I got in 2009 or 2010, and I think it was one of the EVGA Superclocked cards (I remember there was something strange about it when I bought it, and I have to turn the fans up high when I play games or they artifact -- hence having EVGA Precision installed). Unfortunately I don't remember exactly what it was called and there's no model number that I can tell on the card itself. Do I have to just buy a new one? :(

No dice, I'm afraid. The new behavior's a little bit different, though. I get my login screen, and if I wait too long on it, it starts getting artifacting. Then, if I log in, it goes to the black screen.

 It sounds to me that you have 2 problems.The first of which is your drivers.The 4xx and 5xx cards don't play well with the newer drivers.These cards have reached the point with their drivers where"if it ain't broken then don't fix it".The second sounds like overheating which may or may not be caused by the drivers.
 The first step is to do a clean install of driver 314.22 or older.make sure you do a custom install and uncheck the box for nvidia update or you will be right back where you started.Because you say that if you wait too long it starts artifacting,I don't think this will solve all your problems due to high temps.
 To fix the temperature problem,being that you card is about 4 yrs old,you will likely need to apply new thermal paste.There's lots of posts here on how to do it as well as videos on youtube.
 

I have been updating the drivers every time a new one (BETA or WHQL, Desktop or Quadro/Tesla) comes out, and have yet to encounter any issues.
 
It sounds as if you may have a hardware problem.
 
If you could borrow another card and try it with the new drivers, that might tell you.

both 320.49 both 327.23 "played well" with my couple of evga gtx 580 SLI.
 
to be honest I didn't see much difference between the two.
 
My rig: http://www.modsrigs.com/detail.aspx?buildid=28342

_Nite_
327.23 works fine on my GTX 460

I just tried this driver and it seems to be working on my GTX 550 Ti.I was unaware of this driver because it's only been WHQL for 3 days.It looks like nvidia got tired of customers buying new cards and having them crippled by updating the drivers.I had concluded that there would be no new drivers for the 4xx and 5xx cards due to the 320.xx series of drivers.I figured if they can't get it right in 5 tries that they never would.I mean sooner or later they will make newer,faster and more powerful cards that will require a whole new set of drivers of their own.It hasn't happened yet.But,based on this ordeal,that time can't be too far away.
 
 To the OP,RMA the card if you can.If you have no warranty then go ahead and try applying new paste yourself or find someone near you who will.You have nothing to lose.The worst that can happen is you get an air pocket in the paste trapping heat or the paste used will need time to cure and you didn't give it enough time before using it.In both scenarios you will be no worse off than you are now.Just watch your temps.
 
 As far as needing new hardware to be able to run a PCIe 3.0 GPU?The answer is no.Any PCIe card will work just fine.
 

I retract my previous statement.Today driver 327.23 has caused my rig to lock up twice in the first hour of use.Looks like it's back to 314.22 for me.