I currently have a 3870x2 and I'm over clocking the card.  Right now I'm running 860 core and 955 mem.  Stock settings are 825 core and 900 GDDR3 memory.
 
I'd like to add a 3rd 3870, and I only have room for a single-slot cooler on the card.  I was looking at the Sapphire Toxic 3870.  The card comes factory over clocked with the core @800 (since reg 3870 runs @775 core) and 1152 for the GDDR4.
 
does anyone know if the Toxic model will reach 860 core on stock cooling?  Would it even reach 825?  I'm not too worried about the memory, since they are different types anyway, there's not much I can do there.
 
I've been using the CCC to over clock since I understand that by using RivaTuner to go higher than the allowed settings in CCC I would lose the nice idle settings provided by the CCC.  I do use RivaTuner to set the fan speed @40%.

I just found a review of the card over at ProClockers.  Their max o.c. was 864 on the core, so I think I'll be fine there.  I've read that the memory on the 3870x2 can reach 1000 mhz, but do I want to sacrifice the idle efficiency for increased memory bandwidth?