Both of our upgraded Saturn's use to hash rock steady at 560Gh/sec. We have even upgraded our power supplies so each module is on it's own line. Then slowly no matter which firmware we used the hash rate would just very slowly drop and never increase again. Both of our Saturn's are doing this and they are hooked up hashing 100 miles apart from one another. Could it be that the hardware is starting to fail? We never had to mess around with their tuning kit. Apparently their hardware isn't as good as I thought it was if only after 3-4 months starts to behave negatively. I tested the power supplies, made sure all our connections are good. The only thing left is the hardware itself. Very strange our hashing speed would just decrease from 560 all the way to 520 with no intervention at all.
Just checking, but have you tried using a different pool?
I'm getting the hash rate not from the pool, but from the miner page itself.