I was thinking of upgrading today to lion so i can finally use both cards but i guess i shall wait.
Currently im only using one quadro 4000, its relatively stable, but my application can use up to eight GPUs and i would likely to exploit it to the fullest potential.
I sent the one Quadro 4000 in for RMA and received a new card back a couple weeks ago. I have been officially running many multi-GPU cuda test with UVA for my thesis and i have 100-percent uptime and zero kernel panics now.
I guess it was a defective card, its funny cause it would work perfectly in single GPU mode but under dual GPU mode it would act funny.
Anyway, just wanted to confirm the perfectly running status of Dual Quadro 4000 on Lion.