first off, i would go with 2 92mm that way you get air blowing through the whole heatsink, and second off what is your noise preference? If you want silent those fans are ok, but if you want performance then go with a very high CFM fan like the "Tornado" series made by Vantec (but be aware that they are extremely loud
) but they blow so much air in unbelievable(if you decided these, i highly recommend at least a fan controller
)