Yeah, you won't find much out there about the K40. Very few people crack with Teslas since they're slower than their GTX (and now RTX) counterparts at 15x the price. And Kepler is especially garbage for password cracking as it lacks LOP3.LUT; the K40 came out when the AMD R9 290X was king. The only reason you see benchmarks for K80 is because they were the only GPU that EC2 offered at the time. But yeah, K40 performance is pretty abysmal... about 12% slower than its sister GK110 the GTX 780 Ti at ~ 11 GH/s NTLM.
Unfortunately you've already bought the cards... Could I convince you to sell them and buy something else? Looks like they're fetching $150-200 on eBay, so if you unloaded all four you could pick up an RTX 2080 which will be ~ 61% than all four K40s combined with much less complexity and power consumption.
Edit: Dammit Chick3nman, you beat me to it. I knew I shouldn't have stopped typing to get a snack :/
Unfortunately you've already bought the cards... Could I convince you to sell them and buy something else? Looks like they're fetching $150-200 on eBay, so if you unloaded all four you could pick up an RTX 2080 which will be ~ 61% than all four K40s combined with much less complexity and power consumption.
Edit: Dammit Chick3nman, you beat me to it. I knew I shouldn't have stopped typing to get a snack :/