9800GTX+ SLI - windows 7 x64

[mr_sm1th]

Hello everyone,
New to the forums, in desperation to figure this out. I bought another 9800GTX+ to run in SLI, but I can't get the system to boot with both cards and the latest nVidia drivers installed. Both cards work on their own, and both PCIe slots on my board are functional. Here is what I'm running:

2x 9800GTX+
Asus P5N-D motherboard
Intel Core 2 Duo E8500
4 GB Patriot DDR2 800 RAM (4-4-4-12)
Antec Signature 850W PSU
Windows 7 Professional x64

I get past the windows loading screen and then get a black screen with active cursor. I can only boot into safe mode or with only one card installed.
The two cards are slightly different but are the same series, but are not exactly the same. One is an Asus Dark Knight and the other is PNY. The clock speeds are almost identical with the only exception being the GPU clock, 740MHz on one 738 on the other.

Any suggestions? If there's anything I forgot, please ask.
Thanks for looking.
-Nick

 

[Mousemonkey]

Did you start off with no drivers installed?

 

[mr_sm1th]

I have tried uninstalling the drivers and using Driver Cleaner, then booting up with both cards and installing the official nVidia drivers, but this produces the same effect. I have also tried installing one card with the nvidia drivers and then booting up again with the second card installed, same outcome.

 

[Longhaul444]

I have a 9800 GTX+ and a GTS 250 SLI'd and have no problems, But I did a clean install with W7 Ultimate x64, as I replaced my MB and went back to Intel from AMD. The only problem I seem to have is with the temps. 62*C on the 250 seems a bit high to me. Also do you have the newest driver release? The beta version of 196.34 is what I have installed and like I said earlier am having no problems at all with SLI in W7.

 

[mr_sm1th]

I think the problem is that the two cards are incompatible
the older card is a 65nm gpu and the newer is 55nm
They are both 9800GTX+ however, and I thought this would be possible.
Does anyone know for sure if these cards should work in SLI or not?