Okay, so I know this is a bit long, but hear me out if you're interested.
About a year ago, I purchased 2 8800 Ultras and ran them in SLI for a while with no problems, until suddenly something began causing my monitor to give a "going to sleep" message and turn off in the middle of anything I was doing, only to come back on if I restarted my system. I ended up taking one of the GPUs out, since I could run most things with just one, and it fixed whatever was going on.
More recently, my motherboard went out, I got it replaced, and thought maybe it was jus the motherboard all along causing the problem. I put the old GPU back in, running in SLI, only to have the same problem occur. I removed the SLI bridge between the two, and it seems to be considerably more stable. I went online, and found that the most common problem here is with the drivers, so I looked around for a bit and found that one of the most reccomended driver versions for Win7 x64 with two 8800s in SLI was 186.91. I downloaded it, then uninstalled whatever the current newest driver that I had installed was. When it got done installing, it prompted a reboot, and when it booted back up, a Windows notification popped up that said it was looking for device drivers. When it got done, it prompted another reboot, and when I rebooted the second time, the newest drivers were re-installed. Long-story shorter than it could be, I got Driver Sweeper and cleaned out all of the display and PhysX drivers, only leaving the chipset drivers.
Now I reboot again, and it doesn't automatically re-install the latest drivers. I went into the setup for 186.91 and ran it, it finished, I restarted my computer, and a notification popped up saying that my GPUs were SLI-capable. I went to go to the Nvidia Control Panel and it's nowhere to be found. I went back into the folder for 186.91 and ran the "NvCplSetupEng", only to get to a point in the setup where I recieved a message saying "Setup failed to read the required display driver to be used with this package." I went into the "installed programs" list in the control panel to make sure it was there, only to find that there was no entry for "Nvidia Display Driver 186.91" like there had been before with the newer driver. I went online once more and several people suggested installing the Nvidia drivers that come with the windows update.
I went to the Windows Update, and sure enough, it has around 150MB of files it can download, along with some sort of Nvidia Networking Controller, but I'm hesitant to download these because I think it might re-download the newest drivers again along with the Nvidia Control Panel. I don't want the newest drivers, as they seem to cause bugs. I JUST need the NVCP in order to enable SLI, but the installer doesn't want to work for me. Anyone know how I can go about getting this, or does each driver version have its own NVCP version that accompanies it, and I would need to find the one specifically for 186.91?
Also, despite not showing up on the list of drivers, I know I have SOME sort of driver installed, because I started up a game that my onboard graphics wouldn't be able to handle, and it ran decently.
I need to get NVCP in order to enable SLI, but I don't need a new driver version, because they're buggy.
Thanks a million if you read all this, and thanks even more if you can give any info or help!
Oh ok, so you got them from Nvidia.com then? They aren't made by EVGA, ASUS, or anyone else? What I am trying to say is the SLI cards you have are known as reference cards. Hardware manufacturers like EVGA, Asus, and Gigabyte are known as non-reference card manufacturers. I was going to say, if for example, you had a couple of EVGA 8800 Ultras, just go to EVGA.com and download the latest drivers from there because they would have a more specifc driver for your card. But I don't know if these websites would support older graphics cards. You have ancient cards like me (EVGA 9800GTX+). Give that a shot.
EVGA would modify the core drivers from Nvidia to allow certain graphics cards to work (i.e. an overclocked version) or to allow interaction between certain software (i.e. overclocking/system monitoring software). I am 99% sure you will be okay with downloading drivers from EVGA. But before you do that, have you tried to download an earlier version of your graphics drivers? Instead of 186.91, is there a 185.91? By the way, you do have a sufficient power supply in terms of wattage/amperage? As far as conflicts, if any, it would most likely come from the newest version of the graphics driver. The older versions should be fine to use.
dont bother with third party drivers go nvidia.com directly to get drivers
any issues perhaps get a third party tool to then adjust the frequencies to default/stock nvidia reference speeds and try sli
i *HATE* it when manufacturers offer custom rubbish cards with cheap nasty after market coolers or overclocked versions they dont last and cause issues stick with reference cards from whatever brand -- they actually work the way there supposed to