while researching this i discovered another fast fp64 card is the R9 280x by amd/ati. although the memory is weak, only 3GB! But i suppose if you need the numerical accuracy, there's always that, and those cards are like $40 (in the us, on ebay, sold listings), compared to $400 for the titan. if you need 4x the ram though i guess you're stuck paying 10x the price!