Quartus II Fitter advice

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I've made this a subject of many reports to local FAEs and even provided testcases to Altera of designs that won't close timing until it's overconstrained and I've never had anything useful back from them.

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That's too bad, because Altera software people should look at designs that behave the way you described. That's contrary to how Quartus is advertised to work. There might be something in your designs that is fundamentally different from most designs that are used to tune the Fitter algorithms.