ASK HN: Comparing processors - Why do these sites give such different results?

How can I get reliable information on the actual speed in practice of different processors? For example, I'm comparing 2 laptops with these processors: Intel Core i3-2310M AMD A6-3400M According to Passmark's CPU benchmarks, the AMD has much better performance, it gets a 3455 compared to i3's 2566. Yet according to Notebook check, the AMD processor is actually more comparable to the older Intel Pentium T5400. So which processor will actually perform better? How can one get reliable information on different processors? [1]: http://www.cpubenchmark.net/cpu.php?cpu=AMD%20A6-3400M%20APU%20with%20Radeon%20HD%20Graphics [2]: http://www.cpubenchmark.net/cpu.php?cpu=Intel%20Core%20i3-2310M%20@%202.10GHz [3]: http://www.notebookcheck.net/AMD-A-Series-A6-3400M-Notebook-Processor.55753.0.html