I am mining at eligius with BFL 60GH/s miner. Usually (several months, actually) it averages to 60.7 GH/s, but starting last week it shows 59.9 GH/s
Anyone noticed something similar? If it was hardware issue like one core dead, I believe hashrate would decrease significantly more
Check out this thread for more details - sounds like 3 less cores are enabled if you dropped that much.
https://bitcointalk.org/index.php?topic=258643.0