*winces* .. Dunno what Mobo/CPU you have, but considering that mining is not CPU intensive, I can't imagine that package is any more than 50W. That would mean ~300W for a single card...?

I can get FEs for an okay price (compared to current retail), but it's only 10% more hashrate for almost twice the power draw of a tuned 56. I'd be extremely interested in the results of any tweaking you end up doing.