I have a discovered a solution for alot of you out there with IRQ issues.
I believe this is causing the login freeze and black screen issue:
  THIS MIGHT HAVE TO BE REPEATED WITH EACH DRIVER UPDATE
 
1.  go into device manager- go under display adapters go into your GTX 400 series Card and see what says for 
     location.. E.G. "PCI bus 18 "
2. go under system devices
3. you will see two HD audio devices.. check them both to see which one matches your GTX 400 series pci bus
    location.  disable (not uninstall) the one that matches your 400 series card.
4. check under sound devices and it should no longer be there (this step might or might not require a restart)   
  FOR SLI SYSTEMS THERE WILL BE AN HD SOUND DEVICE FOR EACH CARD 
^^ THIS MIGHT HELP TO CLEAR UP YOUR LOGIN FREEZE AND BLACK SCREEN ISSUES
 I ALSO RECOMMEND UNINSTALLING THE SURROUND DRIVERS UNLESS OTHERWISE NEEDED AND CHANGING THE NVIDIA CONTROL PANEL TO "SINGLE DISPLAY PERFORMANCE MODE" (this will help with flickering)  AND SET TO MAXIMUM PERFORMANCE POWER MODE
  now if you want you can follow these proceedures to clean out your drivers) although you might not have to. but
it is a good idea to clean your drivers after this and steps 1-6 are a template on how to uninstall and reinstall display drivers.  GOOD LUCK TO ALL OF YOU AND  I HOPE THIS HELPS
 
 1. Download Driver Sweeper and driver cleaner and install them.  mainly need driver  google them. also down load the latest audio drivers from evga and the latest Nvidia drivers straight from Nvidia. 
2. boot up GO INTO PROGRAMS AND FEATURES IN CONTROL PANEL. Uninstall Nvidia Physx and Nvidia surround driver.  DO NOT UNINSTALL NVIDIA DRIVERS ON NVIDIA CONTROL PANEL YET.
3. Reboot. Go into safe mode (press F8 repeatedly upon power up)
4. While in SafeMode go into program and features now selected Nvidia Drivers then uninstall them. it will then ask you to reboot the computer DO NOT REBOOT YET SELECT NO. 
5.  While still in safemode open Driversweeper select nvidia display and click analyze. when it is done click on clean.  Then open driver cleaner. click on the box that says "use multiple filters" the select Nvidia, Nvida wdm and nvidia stereo.
6. Once you have finished with driver sweeper and driver cleaner reboot back in to regular mode. open device manager and check to see if your display adapter reads "Generic video adapter" or something along those lines and that it is a microsoft driver.  then check your sound drivers to make sure that All 4 Nvidia soundrivers are uninstalled. Once you have verified that all the nvidia drivers are uninstalled REBOOT INTO SAFEMODE. 
7.  WHILE IN SAFEMODE.  Go into open programs and see if there is anything labeled Realtek audio drivers if there is uninstall that. DO NOT REBOOT YET.  Open device manager and go to sound devices and select any remaining audio devices and uninstall them. then open driver sweeper and clean out the left over files. After using driver sweeper you can now Reboot into regular mode. 
8.  After reboot open up device manager and make sure that all the drivers you uninstalled and cleaned out were replaced by Generic Microsoft Drivers.  Then install The nvidia display drivers and disable windows automatic updates.  Now reboot.
9. after you reboot go into device manager and DISABLE the 4 nvidia sound driver the REBOOT BACK INTO SAFEMODE.  Once you are back in safemode open up device manager and uninstall the Nvidia sound drivers.  if they won't uninstall then make sure they are disabled in safemode.  Reboot
10. Now install or reinstall your onboard audio drivers then reboot.

Deggg

I hope Nvidia takes a lesson from this and for their next series makes the onboard sound an option that can be disabled at the hardware level.

+1
 
Causes my system to hang when resuming from standby, so i have to mess around with uninstalling and disabling. Only complaint about 400 series cards.

Perhaps this deserves a sticky until a driver fix is put out? alot of people are having these problems and causing unecessary hate/ RMAs...

Good post.  Thanks!

i hope this worked BTW Thank you

^^^ i used "pci bus 18" as an example
it will be different on every board thats why it says "E.G."
The point is to find the same pci bus for the audio device as the one in use by the video card.. not to disable the actual IRQ 

just a clarification:

for example: you go into device manager and under display adapters you see that your gtx 470 is on pci bus 1 and then you go under system devices and you see two versions of "High defintion audio controller".
You want to disable the audio controller that is using the same PCI bus as the video card.. so what ever audio controller is on again for example PCI Bus 1 then that would be the one to disable..the pci bus on the hd audio controller has to match the one in use by the card.. and it has to be the audio controller listed under "System Devices" NOT the one under "sound video and game controllers" in device manager

^^ it is a conflict and i have the BSOD's to prove it LOL..
but in all seriousness i spoke with evga about this and they are actually talking to Nvidia about it.. so i think you will see some sort of update to the drivers or some sort of utillity put out soon

It worked for me! Thanks alot man!!  

i am glad i could help

@ _illusive_

please list your system specs and include your OS

and are you using a discrete sound card or an onboard one?

what motherboard are you using and what is the pci bus on the sound blaster check under "sound, video and game controllers" in device manager.. and do you also see 4 instances of the nvidia hd sound device under that section

you should be able to safely disable the hd audio controller in system devices the one thta is pci bus 9.. then the 4 instances of nvidia sound devices should disapear in sound video and game controllers

How come I still get locks after doing a clean install of W7 and installing the 260.63s and unselecting the HD audio driver install option?

@deathofkings
are you using HDMI for your video output?