Discarded is a meaningless stat unless you're using getwork (and even then it only matters to the pool operator, not the miner). It is a 100% useless stat on GBT and Stratum. Discards are not rejects, they aren't even shares. It means your software had work prepared to hash but instead it discarded it in favor of newer/fresher work. You aren't wasting any hashes when your miner discards work.
Are you sure? Because my miner says it's running at ~215 GH but the pool page reports only 150 GH
That's more likely your OTHER stats, like the fact that it seems to be getting a ton of HW errors. Discards have NO effect. It is a stat that shouldn't even be made visible anymore because I don't think there's a single pool out there still using getwork.