8800GT SLI & Vista 64 Issues

Thought I might post here before giving up.

I'm trying to SLI my two PNY 8800GT's and I'm running into a roadblock. The driver install is fine but when I go to enable SLI in the nvidia control panel my screen blinks a couple times and hangs with a blinking cursor. After rebooting both devices are disabled and I'm standard VGA mode.

Both cards individually work fine, and my power supply seems to be hefty enough and brand new (Corsair TX650W).

Here's what might be a twist, while both are PNY 512MB 8800GT's, they are different models. I believe the difference is in cooling, though I'm not quite sure if that's all there is to it.

VCG88512GXPB vs VCG88512GXEB

I only noticed they were different upon receiving my order, and the research I've done indicated that different 8800GT's should SLI fine if they have the same memory buffer size.

I've also come across some threads that describe this same exact problem and identifying it as a Vista 64 driver issue and only resolving it by going back to 169 drivers. I've tried downloading the latest few stable drivers without success, and tried the latest Far Cry 2 beta drivers as well. Not exactly willing to down grade my drivers that far back as I know there have been some considerable performance increases in the latest drivers and I don't want to sacrifice that for a shoddy SLI setup.

Has anyone else come across this?

Has anyone else come across this?

Not with the 8800s but I have sli 8700s, and have found trying to get them running properly to be a huge PITA. No real advice, just sympathy for you problem.