Need help with SLI

[KingBing]

I'm sporting the following relevant system specs:

MB: Asus P67 Sabertooth
PSU: Corsair HX750W
CPU: Intel i7 2600K
OS: Windows 7 Ultimate 64 bit

I'm have a Gainward GTX 560Ti Phantom 2Gb as my main card, and I was recently given a Gainward GTX560 Ti 1Gb card.

I've been told that these can run in SLI, although only 1Gb of memory will be used on the 2Gb card, but I'm simply unable to get it to work. Both cards work fine alone in either PCI-E slot, and I can boot up my system and see both GPUs in Nvidia Control Panel, but the secondary card simply won't do anything.

I have installed the newest Nvidia drivers.
I have also attempted to just set the second card as dedicated PhysX in Nvidia control panel, but the card still does nothing, even while doing a PhysX demo.

MSI Afterburner

Using FluidMark I got an amazing 14% GPU usage!

Setup(Sorry for the messy wires, should still be clear enough to see)

 

[vitornob]

Sadly I think you can't run them together due to memory difference
Weirdly you should be able to use it for Physx at least..

 

[KingBing]

I remember using something called CoolBits to enable this thing. Is this still around? Or has it just been dumped, seeing as it's probably 5 years since I used it.

 

[KingBing]

Ok, I've had minor breakthrough, using Coolbits, I got Nvidia Control Panel to tell me my system is SLI capable.

When I go into NCC, I hit enable SLI, and apply. This freezes my PC for a while, and then apparently deletes the Nvidia driver.

Screen switches to a horribly low resolution, and the option to open NCC is gone, restarting does nothing. So I've reinstalled the drivers for my card, this however resets the SLI option, and activating again restarts this whole circus.

 

[Mousemonkey]

Have you tried using any older drivers?

 

[KingBing]

Will try it with 275.33 WHQL

EDIT: Same error as before, sadly.

 

[KingBing]

When I choose to enable SLI, the screen goes black and the NCP hangs, during this time, if I go into device manager, one of the cards is marked with an exclamation mark. If I disable this, and enable it again, SLI will be enabled, and I have SLI capability until I restart my PC, after which the driver needs to be reinstalled.

This works both with the old driver i posted earlier, the newest nvidia driver, and the 290.(something) Nvidia beta driver.

 

[Mousemonkey]

I'm wondering if it has something to do with the different amounts of RAM, things may have changed regarding this or you have a duff card perhaps?

 

[ixlr8]

I had endless problems getting 2 identical 560ti cards to SLI without green flashing on the screen. It ended up being the motherboard memory interleave was not set correctly. I have a 2600K and Z67 motherboard, but the BIOS is the same.
There was also another issue of having a SATA6 device on port 0, and a SATA3 device on port 1. The #1 core would stay at 100%. I moved the SATA3 device to port 5. Also try swapping the the card locations, NVIDIA does some odd stuff with their drivers...